Get ready for the Unit 1 Take-Home Exam
Unit 1: Medical Investigation. Your take-home exam is handed out Thursday, October 1 and due Monday, October 5 at the start of class. It is a printed packet you write in pen. Everything on this page comes from what we did in class, and every answer here is hidden until you open it, so you can check yourself honestly.
- Sitting one (25 minutes). Read the 10 skills below and the Tests compared table. Say each skill out loud in your own words.
- Sitting two (25 minutes). Work the flashcards until you can say every back before you open it, then take Quiz 1 and open each answer only after you have chosen.
- Sitting three (30 minutes). Take Quiz 2, and read one study conversation, answering its practice scenarios before you show the answer.
- Then take the practice test PDF under test conditions and check it with the key at the end. Explain every miss using the skill it matches.
The big ideas of the unit
- Evidence has limits, and good investigators say where their claim stops. A result can support a claim, fail to exclude someone, or be inconclusive. Almost nothing "proves" by itself.
- Observation is not inference. What you saw, heard or measured is different from your explanation of it. Keep them apart in every record.
- Records must be honest and complete. Chain of custody, measured positions, and "not reported" entries let someone else trust and check the work.
- Screening tests and confirmatory tests do different jobs. A presumptive (screening) test says "maybe"; a confirmatory test says "yes"; and only DNA can point to whose.
- Every test can be wrong in two ways. A false positive labels a healthy person; a false negative misses a sick one. They harm different people.
- Compare to a known reference. Blood types, DNA lanes, lab values and tissue slides only mean something when compared to a trusted reference or normal range.
- The body keeps time and records damage. Cooling, stiffening and settled blood give a window for time since death; tissue under a microscope shows what happened inside organs.
- Corroboration closes cases. Independent lines of evidence that agree are stronger than one persuasive clue.
How the take-home exam works
- The Unit 1 Test is now a take-home exam. Period 6-7 gets it Thursday, October 1; Period 1-2 gets it Friday, October 2. Both are due Monday, October 5 at the start of class.
- Printed packet, written in pen, 1000 points in four sections. Section A, multiple choice, open notes (320), then the Thinking Check on how sure you were and why the tempting wrong answers are wrong (80), for 400. Section B, Your evidence: three questions answered from your own case records, citing where each record is (250). Section C, Draw the mechanism: a hand-drawn, labeled drawing of what happened inside the body and a paragraph that walks its arrows (200). Section D, Watch my thinking: your in-class first try and its revision, one honest confusion, and your AI Use Log (150). Paper only: nothing is uploaded.
- First try in class: on handout day, the first 5 minutes go to packet page 2, START HERE IN CLASS, in pen, with no notes. Mr. Mendoza initials it before you leave. Absent on handout day? Do it in class on the day you return.
- Using AI: AI may explain a concept, quiz you, or define a word, and every use goes in your AI Use Log. Do not paste an exam question into AI, do not copy an AI answer, and do not let AI write any part of Sections B, C or D. Every student has a short talk, about 2 minutes, with Mr. Mendoza about two or three of their answers at turn-in on Monday, October 5. This is not a punishment. If you did not log AI use, or your answers do not match your class work, the talk takes longer.
- How to use this page: work the three sittings below as you prepare for Section A, then use the skills checklist and glossary to check your own explanations in Sections B to D.
- It covers what both classes were taught before the exam was handed out. It works for either case: no question depends on the Static or Respawn case details.
- Study tools: the Unit 1 Study Guide and the Unit 1 Practice Test (key at the end), both linked at the bottom of this page and in the "Unit 1 Test prep" box under Sources on each day page.
- The rest of Unit 1 (the Case Closed report days, Oct 1 to Oct 8) is tested on the Unit 2 Test.
Each card names a skill, what you should be able to do, and the mistake students make most. Open the worked example after you have tried it yourself.
Stay safe: PPE first, and the SDS for chemical facts
I can identify when to use PPE and where to look for chemical hazard information.
Put on assigned PPE before touching any sample. Never judge a hazard by look or smell. The safety data sheet (SDS) gives a chemical's hazards, handling, storage and first aid. The procedure and the safety contract do not replace it.
Worked example
Before handling a suspected blood sample, I put on gloves and goggles. If asked about a spill, I check the Safety Data Sheet (SDS) instead of smelling the chemical.
Common mistake: Thinking the safety contract or lab procedure replaces reading the SDS for chemical facts.
Pick the right graph
I can choose the correct type of graph based on the data being displayed.
Histogram: how many values fall in each range (bars touch). Bar graph: separate categories. Line graph: change over time. Scatter plot: whether two measured variables are related.
Worked example
If I have data on heart rate over 10 minutes, I use a line graph.
Common mistake: Using a line graph for separate categories (like blood types of different suspects) instead of a bar graph.
Keep records honest: missing stays visible
I can accurately document evidence and note when information is missing.
Write "unassigned" when no number was given and "not reported" when a time, date or name is missing. Never guess or copy a nearby value. Chain of custody (who had the evidence, when) and package condition (sealed, torn, wet) are separate checks.
Worked example
If a lab report has a blank for the time collected, I write "not reported" rather than guessing.
Common mistake: Guessing or copying a nearby value when a piece of data is unassigned.
Measure where evidence sits
I can measure the exact position of evidence from two fixed reference points.
Measure from two fixed reference points, with units; one distance only puts the item on a circle. Photos do not record a measured position.
Worked example
I record that a phone was found 45 cm from the north wall and 110 cm from the east wall.
Common mistake: Measuring from only one reference point, which only places the object somewhere on a circle.
Tell an observation from an inference
I can distinguish between what I actually observed and what I assume happened.
"Because," "must have," "was trying to" and guesses about feelings signal an inference.
Worked example
Observation: "The beaker is broken on the floor." Inference: "Because someone knocked it off the table."
Common mistake: Including inferences (like "was trying to" or "must have") in an official evidence record.
Compare to known references and use exclusion language
I can compare test results to known references and correctly use the word "exclude".
No reference, or an unlabeled one, means inconclusive. ABO: clumping in anti-A means A marker; in anti-B means B marker; both means AB; neither means O. A shared blood type fails to exclude; it never identifies. STR lanes: a reference is not excluded only if every band lines up; one clearly different band excludes it.
Worked example
If a blood sample from the scene is type A and the suspect is type O, the suspect is excluded.
Common mistake: Thinking that a matching blood type identifies a specific person, rather than just failing to exclude them.
Read screening results for what they really say
I can interpret presumptive test results and understand false positives/negatives.
Presumptive positive means the target may be present and needs a confirmatory test. Presumptive negative means "not detected by this screen," not "absent." False positive: a person without the condition tests positive. False negative: a person with the condition tests negative.
Worked example
A positive Kastle-Meyer test means the sample might be blood and needs a confirmatory test, not that it is definitely blood.
Common mistake: Assuming a presumptive negative means the target is entirely absent, rather than just "not detected."
Flag lab values against their reference range
I can compare a patient's lab value to the normal range and flag it as high or low.
Check both limits. Below the lower limit is low; above the upper limit is high; inside the range is normal even if close. One flag is a question, not a cause.
Worked example
If a patient's glucose is 120 mg/dL and the reference range is 70-100 mg/dL, I flag it as "high."
Common mistake: Assuming a flag is a definite diagnosis rather than just a lead to investigate further.
Estimate time since death from body cooling, as a window
I can calculate a time since death window using body cooling rates.
Class rule: the body starts near 37 °C and early on cools about 1 to 1.5 °C per hour. Degrees lost = 37 minus body temperature. Divide by 1.5 for the short end and by 1 for the long end. State the assumptions.
Worked example
A body is found at 29 °C. 37 - 29 = 8 degrees lost. 8 / 1.5 is about 5.3 hours (short end) and 8 / 1 = 8 hours (long end). Window: about 5 to 8 hours, stated with the assumption that the body started near 37 °C.
Common mistake: Giving an exact time of death instead of a window, or forgetting to state the assumption (e.g., normal starting temp of 37°C).
Read tissue slides against a normal reference
I can compare a tissue sample slide to a normal reference slide before declaring damage.
Compare to normal tissue first. Staining time, section thickness and cutting angle change the look, not the tissue: check preparation before calling damage.
Worked example
Before deciding a lung tissue slide shows disease, I compare it to a slide of healthy lung tissue.
Common mistake: Calling damage without checking if preparation differences (like staining time or section thickness) caused the tissue to look different.
Read across one row to see how a test works and where its claim must stop. Read down the last column to see who runs it for a living.
| The test | What it looks for | How it works | The signal you see | What positive and negative mean | What it cannot tell you | Who uses it at work |
|---|---|---|---|---|---|---|
| Kastle-Meyer (presumptive) | Heme (iron part of hemoglobin in red blood cells) | Swab stain + phenolphthalin + hydrogen peroxide | Quick pink color | Pos: presumptive blood (needs confirm). Neg: not detected. | False positives (plant material/metals). Does not say human or whose. | Crime scene technician, forensic scientist |
| Luminol (presumptive) | Traces of heme | Sprayed on surface, reacts with iron | Faint blue glow in the dark | Pos: possible trace blood. Neg: not detected. | False positives (bleach, some metals). Does not by itself destroy DNA; spraying can dilute or spread a stain, so DNA samples are collected first where possible. | Crime scene technician |
| ABO blood typing | A and B markers (antigens) on red blood cells | Mix blood with anti-A and anti-B serums | Agglutination (clumping) | Anti-A only: type A. Anti-B only: type B. Both: type AB. Neither: type O. | Class evidence; can exclude but never identify a single person. | Medical laboratory scientist, forensic scientist |
| STR DNA Profiling | Short tandem repeats (STRs) in DNA | PCR copies STRs, electrophoresis sorts by size | Bands or peaks at particular sizes in lanes | Pos (match): not excluded. Neg (diff): excluded. | Needs a labeled reference; easily contaminated. | DNA analyst, forensic scientist |
| ELISA | Specific antibody or antigen | Target coats well, sample added, wash, enzyme-linked antibody, wash, substrate added | Color in the well | Pos: signal above the cutoff, target may be present (false positives happen; confirm). Neg: below the cutoff, not detected (does not prove absence). | False positives/negatives; past vs. current infection unclear. | Medical laboratory scientist |
| Autopsy / Gross anatomy | Large organ structures and visible abnormalities | Medical examiner visually inspects body and organs | Visible damage, abnormal size/shape | Pos: unusual finding. Neg: normal appearance. | Does not show microscopic or chemical details. | Forensic pathologist, medical examiner |
| Histology | Microscopic tissue structure | Thin tissue slice is stained (e.g., H&E) and viewed under microscope | Purple/blue (nuclei) and pink (other) | Pos: abnormal structure/damage. Neg: normal structure. | Slide prep (thickness, stain time) can mimic damage. | Histotechnologist, forensic pathologist |
| Lab values (blood/urine) | Chemical levels | Sample run through analyzer and compared to reference range | Value printed next to range | Pos (flag): High or Low. Neg: Normal. | One flag is a lead, not a diagnosis. | Medical laboratory scientist, emergency team |
D1. Presumptive blood tests (Kastle-Meyer and luminol)
- Looks for: heme, the iron-containing part of hemoglobin in red blood cells.
- Kastle-Meyer, how it works: a swab of the stain gets a drop of colorless phenolphthalin reagent, then a drop of hydrogen peroxide. Heme speeds up a reaction that turns the reagent into phenolphthalein, which is pink in the test's basic (alkaline) solution.
- Signal: a quick pink color means presumptive positive.
- Luminol: sprayed on a surface; iron in heme helps it react and give off a faint blue glow in the dark, useful for finding traces.
- Limits: both are screens. Other things can react (some plant material, some metals, bleach for luminol), so a positive needs a confirmatory test. A negative means "not detected," not "no blood." Neither test says whose blood or even whether it is human.
- Class sentence to remember: only a confirmatory test says blood, and only DNA says whose.
D2. ABO blood typing (agglutination)
- Looks for: A and B markers (antigens) on the surface of red blood cells.
- How it works: a drop of blood is mixed with anti-A serum in one well and anti-B serum in another. Antibodies in the serum grab matching markers and link cells together.
- Signal: agglutination, visible clumping of cells.
- Reading it: anti-A clumps only: type A. Anti-B only: type B. Both: type AB. Neither: type O. (The Rh marker is tested separately with anti-D.)
- Limits: many people share each blood type, so it is class evidence: it can exclude a person, never identify one.
D3. DNA profiling with STRs
- Looks for: short tandem repeats (STRs), short DNA sequences repeated a different number of times in different people.
- How it works: DNA from a sample is copied many times at chosen locations (PCR), then the copies are sorted by size (electrophoresis). Each person has two versions (one from each parent) at each location.
- Signal: bands (or peaks) at particular sizes in each lane.
- Reading it: compare the questioned sample's bands with each known reference, band by band. Any clearly different band excludes that reference. Every band lining up means "not excluded" (in real labs, many locations and statistics are used before calling a match).
- Limits: needs a labeled, trusted reference; contamination and mix-ups make results worthless, which is why custody records matter.
D4. ELISA (from the John Carroll debate case)
- Looks for: a specific antibody or antigen in a sample.
- How it works: wells are coated with the target; the sample is added; anything that binds stays and everything else is washed away; an enzyme-linked antibody is added, then a substrate that the enzyme turns into a colored product.
- Signal: color in the well; more target, more color.
- Reading it: compare each well to a cutoff, and only after the positive control shows color and the negative control stays clear.
- Limits: false positives and false negatives happen; an antibody result can mean current or past infection.
D5. Time since death: the three clocks
- Algor mortis: body cooling. Class rule above; gives a window, bent by room temperature, clothing and body size.
- Rigor mortis: temporary stiffening of muscles after death that comes and goes on a rough schedule over the first day or two.
- Livor mortis: blood settling to the lowest parts of the body after death, becoming fixed after several hours. If the pattern does not match how the body was found, the body was moved.
- Big idea: one clock persuades; three clocks that agree corroborate.
D6. Lab values and reference ranges
- A blood or urine test value is compared with its reference range (the normal range printed beside it). Flag high or low; a flag is a lead to follow, not a diagnosis.
D7. Autopsy and gross anatomy (Period 1-2 hands-on; Period 6-7 examiner's record)
- Gross anatomy means structures you can see without a microscope. The heart has four chambers (right atrium, right ventricle, left atrium, left ventricle) and four valves (tricuspid, pulmonary, mitral, aortic). Organ findings lead to the questions tissue slides answer.
D8. Histology (tissue slides)
- A thin slice of tissue is stained so parts show up: the common hematoxylin and eosin stain colors nuclei purple-blue and much of the rest pink.
- The four tissue families: epithelial (linings and coverings), connective (support, including blood and bone), muscle (movement), nervous (signals).
- Always compare to a normal reference slide, and rule out preparation problems before calling damage.
- PPE (Personal Protective Equipment)
- Gear worn to minimize exposure to hazards.Example: Wearing gloves and goggles before touching a blood swab.
- SDS (Safety Data Sheet)
- A document containing chemical hazards, handling, and first aid information.Example: Checking the SDS before using luminol.
- Chain of custody
- A documented record of who had the evidence and when.Example: Signing the log when taking a swab from the evidence locker.
- Exhibit
- A piece of evidence presented in a case.Example: Exhibit A, the bloody shirt.
- Observation
- What you actually saw, heard, or measured.Example: The liquid in the well turned pink.
- Inference
- A conclusion or guess based on observations.Example: The liquid turned pink, so the suspect must have cut themselves.
- Reference point
- A fixed location used to measure where evidence sits.Example: The north wall of the classroom.
- Known reference
- A sample from a known source used for comparison.Example: A blood sample drawn directly from the suspect.
- Exclusion
- Ruling someone out as the source of evidence.Example: The blood type didn't match, resulting in the suspect's exclusion.
- Inconclusive
- A result that doesn't prove or disprove anything, often due to missing references.Example: Finding type A blood but having no suspect references.
- Presumptive test
- A screening test that says a substance might be present.Example: The Kastle-Meyer test.
- Confirmatory test
- A follow-up test that identifies the substance itself: for a stain it can say "yes, this is blood," which a presumptive screen cannot. It still has limits, and it does not say whose.Example: The case record's phrase "presumptive positive for blood; confirmatory testing required" sends a swab forward for a confirmatory test.
- False positive
- A test incorrectly indicates a condition is present.Example: Kastle-Meyer turns pink from horseradish, not blood.
- False negative
- A test incorrectly indicates a condition is absent.Example: An ELISA misses a low-level infection.
- Agglutination
- The visible clumping of cells.Example: Clumping when anti-A serum is added to type A blood.
- Antigen
- A molecule that an antibody recognizes and binds; in ABO typing it is the A or B marker on the red blood cell surface, and in an ELISA it is the target coated in the well.Example: The A marker on a red blood cell.
- Antibody
- A protein that binds to a specific antigen.Example: Anti-A antibodies in the typing serum.
- STR (Short Tandem Repeat)
- Short DNA sequences repeated differently in different people.Example: The DNA sections sorted in electrophoresis.
- PCR
- A technique to copy DNA many times.Example: Making enough copies of STRs to show up on a gel.
- Electrophoresis
- A method to sort DNA fragments by size.Example: Running the gel to see the DNA bands.
- Cutoff
- The threshold value used to decide if a result is positive or negative.Example: Comparing an ELISA well color intensity to the cutoff well.
- Control
- A sample with a known expected result used to check the test.Example: An ELISA positive control turning blue.
- Reference range
- The normal values for a lab test.Example: A normal glucose range of 70-100 mg/dL.
- Algor mortis
- Body cooling after death.Example: The cooling clock gives a time window, never an exact time of death.
- Rigor mortis
- Stiffening of muscles after death.Example: Noting the victim's arms were stiff.
- Livor mortis
- Settling of blood after death.Example: Seeing purple pooling on the victim's back.
- Gross anatomy
- Structures you can see without a microscope.Example: Examining the four chambers of the heart.
- Histology
- The study of tissues under a microscope.Example: Looking at H&E stained lung slices.
- Stain
- A dye used to make tissue parts visible.Example: Hematoxylin and eosin (H&E).
- Tissue family
- The four main types of tissue (epithelial, connective, muscle, nervous).Example: Identifying a slide as muscle tissue.
- Corroboration
- Multiple independent lines of evidence that agree.Example: Algor, rigor, and livor mortis all pointing to the same time of death.
- Claim ceiling
- The limit of what evidence can actually prove.Example: A presumptive test can't claim it's definitely human blood.
- Manner of death
- The category of death (natural, homicide, suicide, accident, undetermined).Example: The coroner ruling it an accident.
- Cause of death
- The specific medical reason for death.Example: Heart failure.
What does a positive Kastle-Meyer test mean?
Presumptive positive for blood (needs a confirmatory test); it does not prove it is human or whose it is.
How do you read ABO blood typing results?
Look for agglutination (clumping). Clumping in anti-A = Type A. Clumping in anti-B = Type B. Both = AB. Neither = O.
What is the main limit of blood typing?
It is class evidence. It can exclude a person, but it can never identify one person specifically.
How do you determine if an STR DNA profile matches?
Compare the questioned sample's bands with the known reference. Every band must line up to say "not excluded." One clearly different band excludes the reference.
What does a false positive mean?
A person or sample without the condition/target tests positive.
What does a false negative mean?
A person or sample with the condition/target tests negative.
What are the three clocks for estimating time since death?
Algor mortis (cooling), rigor mortis (stiffening), and livor mortis (blood settling).
How do you calculate the algor mortis time window?
37°C minus body temp = degrees lost. Divide by 1.5 for the short end, and by 1 for the long end (in hours).
What does livor mortis tell you beyond time since death?
If the pattern of settled blood doesn't match how the body was found, the body was moved.
What is the difference between an observation and an inference?
An observation is what you directly saw/measured. An inference is a guess or explanation based on the observation (e.g., "because").
What is a claim ceiling?
Knowing the limits of your evidence; e.g., stating a result "fails to exclude" rather than claiming it "proves" guilt.
Why must you compare tissue slides to a normal reference?
To rule out preparation differences (like staining time or slice thickness) before calling it tissue damage.
What does "inconclusive" mean?
The test doesn't give a clear answer, often because a labeled, trusted reference is missing.
Choose your answer, then open it. The answer names the skill it checks and shows the working when there is math, so a miss tells you what to review.
1. You are assigned to test an unknown liquid found in a beaker. Before beginning, where should you look to understand the hazards of the chemical?
- AThe label on the evidence bag
- BThe laboratory procedure steps
- CThe classroom safety contract
- DThe Safety Data Sheet (SDS)
Show the answer
Answer: D. (Skill 1: Stay safe: PPE first, and the SDS for chemical facts)
2. You want to graph the relationship between the outside temperature and the number of hours it takes for a body to reach ambient temperature. Which graph is best?
- AA scatter plot
- BA line graph over time
- CA histogram of the hours
- DA bar graph with one bar per day
Show the answer
Answer: A. (Skill 2: Pick the right graph)
3. When sketching a crime scene, how should you record the position of a weapon?
- AMeasuring the distance from one corner of the room only
- BTwo distances from fixed reference points, with units
- CEstimating the distance by eye and writing "about 3 feet"
- DTaking a photograph of it from the doorway
Show the answer
Answer: B. (Skill 4: Measure where evidence sits)
4. Which of the following statements is an inference rather than an observation?
- AThe liquid in the test tube turned pink after 10 seconds.
- BThe victim was trying to escape when the glass broke.
- CThe body temperature was 32 degrees Celsius.
- DThere are three visible bands in lane 4 of the gel.
Show the answer
Answer: B. (Skill 5: Tell an observation from an inference)
5. A blood stain at a scene is type O. Suspect A is type A, and Suspect B is type O. What is the correct conclusion?
- ASuspect A is excluded; Suspect B is not excluded.
- BBoth suspects are excluded by the blood type.
- CThe result is inconclusive without more testing.
- DSuspect B is the source of the blood at the scene.
Show the answer
Answer: A. (Skill 6: Compare to known references and use exclusion language)
6. A Kastle-Meyer test turns pink when applied to a stain. What does this mean?
- APresumptive positive for blood; a confirmatory test comes next.
- BThe test gave a false negative and should simply be repeated.
- CThe stain is definitely human blood, so no further test is needed.
- DThe stain is not blood, and the swab can be discarded.
Show the answer
Answer: A. (Skill 7: Read screening results for what they really say)
7. A patient's heart rate is 110 bpm. The reference range on the chart is 60-100 bpm. How should this be flagged?
- AInconclusive
- BNormal
- CHigh
- DLow
Show the answer
Answer: C. (Skill 8: Flag lab values against their reference range)
8. A body is found with a temperature of 28°C. Assuming a normal starting temperature of 37°C, what is the estimated time since death window? (Cooling rate: 1 to 1.5°C per hour)
- A4 to 6 hours
- B6 to 9 hours
- C2 to 4 hours
- D9 to 15 hours
Show the answer
Answer: B. (Skill 9: Estimate time since death from body cooling, as a window)
37 - 28 = 9. 9 / 1.5 = 6 hours. 9 / 1 = 9 hours. Window: 6 to 9 hours.
9. You observe a tissue slide that looks darker and thicker than the reference slide. Before diagnosing a disease, what should you consider?
- AWhether the patient had a false positive on a previous screening test.
- BThe patient's blood type and Rh factor from the lab report.
- CThe chain of custody for the slide from the lab to the classroom.
- DSlide preparation differences, such as stain time and thickness.
Show the answer
Answer: D. (Skill 10: Read tissue slides against a normal reference)
Choose your answer, then open it. The answer names the skill it checks and shows the working when there is math, so a miss tells you what to review.
1. A forensic technician runs an STR DNA profile on a bloodstain found at a scene and compares it to Suspect X. Seven of the eight bands line up perfectly, but one band in the suspect's lane is clearly missing from the evidence lane. What is the correct conclusion and why?
- ASuspect X is excluded; one clearly different band excludes a reference.
- BThe result is inconclusive because a reference was not used.
- CSuspect X is the source because the majority of bands match.
- DSuspect X is not excluded because one missing band is within the normal error margin.
Show the answer
Answer: A. (Skill 6: Compare to known references and use exclusion language)
2. A body is discovered in a 20°C room with a core temperature of 25°C. The medical examiner notes that livor mortis is fixed on the victim's back, but the body was found lying face down. What can be concluded?
- AThe body has been dead for 2 to 3 hours and was moved before the livor mortis pattern fixed.
- BThe body has been dead for 4 to 6 hours and was not moved.
- CThe body has been dead for 8 to 12 hours and was moved after livor mortis became fixed.
- DThe body has been dead for 8 to 12 hours and was not moved.
Show the answer
Answer: C. (Skill 9: Estimate time since death from body cooling, as a window)
37 - 25 = 12 degrees lost. 12 / 1.5 = 8. 12 / 1 = 12. Window: 8 to 12 hours, which agrees with fixed livor, at least about 8 to 12 hours. Fixed livor on the back while the body lies face down means the body was moved after the pattern fixed.
3. An ELISA test for a rare virus comes back with a pale color in the patient well, but the positive control well is clear. What should the technician do next?
- AReport a false positive for the patient and move on.
- BInvalidate the run and repeat it; the positive control failed.
- CReport a positive result for the virus based on the pale color.
- DReport a negative result for the virus because the color is pale.
Show the answer
Answer: B. (Skill 7: Read screening results for what they really say)
4. A suspect's blood type is AB. The blood at the scene shows no agglutination in anti-A serum and no agglutination in anti-B serum. Using proper exclusion language, what can you state?
- AThe blood at the scene is type O, so the suspect is not excluded.
- BThe blood at the scene is type AB, so the suspect is not excluded.
- CThe blood at the scene is type AB, so the suspect is excluded.
- DThe blood at the scene is type O, so the suspect is excluded.
Show the answer
Answer: D. (Skill 6: Compare to known references and use exclusion language)
5. A detective finds a red stain and sprays luminol, which faintly glows blue. He writes in his report, "Found human blood on the carpet." What two errors did he make regarding the evidence's claim ceiling?
- ALuminol only glows for bleach, not blood, and he failed to use a reference point.
- BLuminol is a confirmatory test, but he forgot to check the SDS, and he made an observation instead of an inference.
- CLuminol is a presumptive screen (not confirmatory), and even if it is blood, the test cannot say it is human.
- DLuminol looks for DNA, not blood, and he should have used the Kastle-Meyer test for human blood.
Show the answer
Answer: C. (Skill 7: Read screening results for what they really say)
Two hosts walk through the unit and stop for practice scenarios. Answer each scenario yourself before you show the answer.
Audio 1 Transcript: From Scene to Lab
Alex: Welcome back, everyone! Today, we’re following a fictional case from the very beginning, the scene, all the way to the lab. We’ll talk about how professionals gather evidence correctly. We're covering skills 1 through 5 from Mr. Mendoza's Unit 1 Test Focus.
Sam: That’s right. Let’s set the scene: A mysterious liquid is found on a lab bench. Before our investigator even steps close, what do they need? PPE. That stands for Personal Protective Equipment, things like gloves, goggles, and lab coats.
Alex: And they don't just guess what's dangerous. They check the SDS. That's the Safety Data Sheet, a document that tells you exactly what a chemical's hazards are, how to handle it, and first aid steps. You never judge a hazard just by how it looks or smells.
Sam: Exactly! Now, the investigator needs to record where the puddle is. They don't just snap a photo. Photos don't record a measured position. You have to measure from two fixed reference points, like two walls that won't move. If you only use one distance, the item could be anywhere on a circle around that point. Two distances lock it in place.
Alex: Let's pause for our first practice scenario!
(Sound effect: chime)
Alex: An investigator finds a dropped phone at a scene. They write down, "Phone is 5 feet from the door." What’s wrong with this measurement?
Think first, then show the answer
Sam: Okay, here's the answer. They only used one reference point. They need to measure from two fixed reference points, like the door and the corner of the room, so someone else can find the exact spot later.
Alex: Nice. So our investigator logs the liquid. They have to keep honest records. If a piece of info is missing, they make it visible. If a form asks for a time but they don't know it, they write "not reported." If a form asks for a patient number that hasn't been given yet, they write "unassigned." Never guess or copy a nearby value.
Sam: Right. Then they package it up. They note the "package condition", is the bag sealed? Is it torn or wet? This is separate from the "chain of custody." Chain of custody is a list of exactly who had the evidence and when. It lets anyone check that the evidence was accounted for at every handoff. A gap in it is recorded and checked; by itself it does not prove or disprove tampering.
Sam: Now the evidence is in the lab. The tech looks at the puddle and writes in their notebook, "The suspect was trying to hide this liquid because they spilled it."
Alex: Whoa, stop right there! That is an inference. An inference is a guess or explanation about what happened, using words like "because," "must have," or "was trying to." An observation is just what you saw, heard, or measured, like "There is a puddle of liquid on the bench." Keep your guesses out of the official record.
Sam: So true. Finally, the lab runs tests and gets a bunch of data. They need to pick the right graph to show it. If they are showing how many samples fall into different weight ranges, they use a histogram, where the bars touch. If they have separate categories, they use a regular bar graph. For change over time, it's a line graph. And to see if two measured variables are related, it's a scatter plot.
Alex: Let's do our final practice scenario!
(Sound effect: chime)
Alex: The lab tracks the temperature of a sample every hour for 24 hours. Which graph should they use to show this data?
Think first, then show the answer
Sam: The answer is a line graph! Whenever you are tracking a change over time, a line graph is the way to go.
Alex: Great job! To wrap up, remember the 6 Rs to study: Record, Reduce, Review, Reflect, Recite, Revise. See you next time!
Audio 2 Transcript: Is it Blood?
Alex: Hey everyone! Today we're talking about blood. Well, things that look like blood. When investigators find a red stain, they can't just say, "Yep, that's blood." They have to test it. We are covering skills 6 and 7 and methods D1 and D2 from Mr. Mendoza's test focus.
Sam: First up, they use a presumptive test. "Presumptive" means it's a screening test, it just says "maybe." A common one is the Kastle-Meyer test. It looks for heme, the iron part of red blood cells. You swab the stain, add a colorless liquid called phenolphthalin, and then add hydrogen peroxide. If it turns a quick pink color, that’s a presumptive positive.
Alex: Another presumptive test is luminol. You spray it in the dark, and if it hits heme, it gives off a faint blue glow. But here's the catch with both of these: they are just screens. Other things can make them react, like some metals or even plant material. So a presumptive positive just means the target might be there. You absolutely need a confirmatory test, a test that says "yes, this is blood."
Sam: Let's hit a practice scenario!
(Sound effect: chime)
Sam: An investigator tests a red stain with Kastle-Meyer. It turns pink. They write in their report, "Confirmed human blood found at scene." What is wrong with this?
Think first, then show the answer
Alex: The answer is: Kastle-Meyer is only a presumptive test. It means "maybe." It doesn't confirm it's blood, and it definitely doesn't tell you if it's human. Only a confirmatory test says it's blood, and only DNA says whose blood it is!
Sam: What about a negative result? A presumptive negative just means the target was "not detected by this screen." It does not mean the target is completely absent. And tests can be wrong! A false positive is when a healthy person (or a non-blood stain) tests positive. A false negative is when a sick person (or real blood) tests negative.
Alex: Time for another practice scenario!
(Sound effect: chime)
Alex: A patient actually has a disease, but their screening test comes back saying they don't have it. What kind of error is this?
Think first, then show the answer
Sam: That's a false negative. The patient has the condition, but the test gave a negative result.
Alex: Okay, let's say a confirmatory test said blood, and a human-specific test said human. Next, we might try ABO blood typing. We're looking for A and B markers, called antigens, on the outside of the red blood cells.
Sam: We do this by mixing a drop of the blood with "anti-A" serum in one well, and "anti-B" serum in another well. The serum has antibodies that grab matching markers and clump the cells together. This clumping is called agglutination.
Alex: If it clumps in the anti-A well only, it's Type A blood. If it clumps in anti-B only, it's Type B. If it clumps in both, it's Type AB. If it clumps in neither, it's Type O.
Sam: But remember skill number 6: compare to known references and use exclusion language! Many people share the same blood type. So, blood typing is class evidence. It can exclude a person, meaning we can prove the blood didn't come from them, but it can never identify a single specific person.
Alex: Final practice scenario!
(Sound effect: chime)
Alex: Blood at a scene clumps in the anti-B well only. A suspect has Type B blood. Does this prove the suspect left the blood?
Think first, then show the answer
Sam: The answer is no! The blood is Type B, so the suspect is not excluded. But millions of people have Type B blood. A shared blood type fails to exclude, but it never identifies.
Alex: Awesome. Remember your 6 Rs to study: Record, Reduce, Review, Reflect, Recite, Revise. Catch you next time!
Audio 3 Transcript: Reading the DNA and the ELISA
Alex: Welcome back! Today we are getting into the really specific tests: DNA profiling and the ELISA test. We are looking at methods D3 and D4 from Mr. Mendoza's list.
Sam: Let's start with DNA. We look at STRs, which stands for short tandem repeats. These are tiny pieces of DNA that repeat over and over, and different people have a different number of repeats.
Alex: We take a tiny sample of DNA and use PCR to copy it millions of times. Then, we use a machine to sort those DNA pieces by size. This sorting is called electrophoresis. The result looks like a column of little lines, called bands, in a lane.
Sam: Since you get DNA from both parents, a person usually has two bands in their lane for every location tested. To read the DNA, you compare the bands from the evidence to the bands of a known reference person, band by band. If even one band is clearly different, you can exclude that reference. It is not them. But if every band lines up perfectly, they are "not excluded."
Alex: Practice scenario one!
(Sound effect: chime)
Alex: An evidence DNA lane has bands at positions 5 and 10. Suspect A has bands at 5 and 11. Suspect B has bands at 5 and 10. What is your conclusion?
Think first, then show the answer
Sam: The answer is: Suspect A is excluded because their band at 11 does not match the evidence band at 10. Suspect B is not excluded because every band lines up.
Alex: Perfect. Now let's talk about the ELISA test. This test looks for a specific antibody or antigen in a sample. It uses a plastic plate with tiny wells.
Sam: First, the wells are coated with the target. You add the patient's sample. If they have the matching antibody, it sticks. Everything else gets washed away. Then you add a second antibody that has an enzyme linked to it, and wash it again. Finally, you add a substrate. The enzyme turns that substrate into a visible color! More color means more target is there.
Alex: But you can't just look at the color and guess. You compare the color in the well to a specific "cutoff" level. And before you can trust any patient results, you have to check your controls. You must have a positive control (which should turn color) and a negative control (which must stay clear).
Sam: Let's practice!
(Sound effect: chime)
Sam: You run an ELISA. The patient's well turns blue. But you look at the negative control well, and it is also blue! Can you trust the patient's result?
Think first, then show the answer
Alex: The answer is no! The negative control must stay clear. If it turned blue, something went wrong, maybe a bad wash step, so all the results on that plate are invalid.
Alex: ELISA results can have errors, too. A false positive is when a healthy person tests positive. A false negative is when a sick person tests negative. These errors harm different people. A false positive might mean a healthy person gets unnecessary, scary treatment. A false negative means a sick person gets sent home and doesn't get the medicine they need.
Sam: Let's do our last practice scenario.
(Sound effect: chime)
Sam: A student forgets to do the wash steps during their ELISA. Will this cause a false positive or a false negative, and why?
Think first, then show the answer
Alex: The answer is a false positive! If you don't wash away the unattached enzymes, they will sit in the well and turn the substrate a color, even if the patient didn't have the target antibodies.
Sam: Great explanation. End your study session with the 6 Rs: Record, Reduce, Review, Reflect, Recite, Revise. See you next time!
Audio 4 Transcript: Time Since Death and Tissue
Alex: Hello! Today is all about what a body can tell us after death. The body actually keeps time and records damage. We're looking at skills 8 through 10, and methods D5 through D8.
Sam: Let's talk about the three clocks of death. First is livor mortis. This is when blood settles to the lowest parts of the body, causing a purplish color. If the blood pattern doesn't match the way the body is lying, it means the body was moved after death.
Alex: The second clock is rigor mortis. This is the temporary stiffening of muscles that happens after death. It comes and goes on a rough schedule over the first day or two.
Sam: The third clock requires some math: algor mortis, or body cooling. Mr. Mendoza's class rule is that a body starts near 37 degrees Celsius, and cools about 1 to 1.5 degrees per hour early on. This gives us a time window.
Alex: To do the math: take 37 and subtract the body's current temperature. That tells you the degrees lost. Then, you divide the degrees lost by 1.5 to get the short end of the window. You divide the degrees lost by 1 to get the long end of the window.
Alex: Now, we have to state the assumptions. We are assuming the body was exactly 37 degrees when they died, and we are assuming the room temperature didn't change the cooling rate drastically.
Sam: Practice scenario time! Get ready to calculate!
(Sound effect: chime)
Sam: A body is found at 25 degrees Celsius. What is the cooling window?
Think first, then show the answer
Alex: 37 minus 25 is 12 degrees lost. 12 divided by 1.5 is 8. 12 divided by 1 is 12. The window is 8 to 12 hours since death.
Sam: Once the body goes to autopsy, they look at gross anatomy, things you can see without a microscope. For example, the heart has four chambers: the right and left atrium on top, and the right and left ventricle on the bottom. It also has four valves: tricuspid, pulmonary, mitral, and aortic.
Alex: They also test fluids like blood and urine. When you get a lab value back, you have to flag it against its reference range (the normal range). You check both the upper and lower limits. If it's below the lower limit, it's low. Above the upper limit, it's high. If it's inside the range, even if it's right on the edge, it's normal.
Sam: Finally, they look at histology, tissue slides under a microscope. There are four tissue families: epithelial (which are linings), connective (support, like bone and blood), muscle (for movement), and nervous (for signals).
Alex: Tissues are stained to make parts show up, like making nuclei turn purple. But to read a slide, you always compare it to a normal reference slide first. And before you say the tissue is damaged, you have to rule out preparation problems! Staining it too long or cutting it weirdly changes how it looks, not the actual tissue.
Sam: Excellent. Keep studying with the 6 Rs: Record, Reduce, Review, Reflect, Recite, Revise. Bye!
Audio 5 Transcript: The Debate over Evidence
Alex: Welcome to the investigation debate desk! Today, Sam and I are arguing about how much evidence you actually need to close a case.
Sam: I'm taking the side of speed. If we get a strong presumptive test result, that should be enough to make a conclusion and close the case! Let's say we find a red stain, we use the Kastle-Meyer test, and boom, it turns pink immediately. The chemical phenolphthalin reacted, hydrogen peroxide did its thing, it's positive. Why wait weeks for DNA? We have our answer!
Alex: I completely disagree. Your claim is hitting a major ceiling. You're forgetting the big idea of Unit 1: evidence has limits, and good investigators say where their claim stops.
Sam: What's the limit on a pink Kastle-Meyer test? It looks for heme!
Alex: The limit is that it's a screening test! A presumptive positive just means the target, heme, might be there. Other things, like plant material or certain metals, can cause that same pink reaction. It's a false positive risk.
Sam: Okay, but what if we do an ABO blood type test? If the suspect is Type A, and the blood at the scene agglutinates, or clumps, in the anti-A well, they match. Case closed, it's the suspect's blood.
Alex: Wrong again! You aren't using your exclusion language. Blood typing is class evidence. You can say the suspect is not excluded, because they both have Type A blood. But millions of people have Type A blood. A shared blood type fails to exclude, but it never identifies. Your claim went way higher than the evidence allows.
Sam: So you're saying I can't prove anything?
Alex: I'm saying almost nothing "proves" by itself. You need a confirmatory test to say it is blood, and then DNA profiling with STRs, those short tandem repeats, to ask whose. And even then, what you really need is corroboration.
Sam: Corroboration? You mean independent lines of evidence that agree?
Alex: Exactly! One clock persuades, three clocks corroborate. If the algor mortis window says 4 to 6 hours, rigor has spread past the jaw and fingers but is not complete, and livor is visible but still fades when pressed (under about 8 hours), all three clocks allow the same 4 to 6 hour window. That agreement is what makes it strong evidence.
Sam: Okay, let's look at what we both got right today. I was right about how the Kastle-Meyer test works (phenolphthalin and hydrogen peroxide turning pink) and how ABO blood typing works (agglutination in the anti-A well).
Alex: And I was right about the limits of that evidence. Presumptive tests say "maybe," and blood typing only excludes, it never identifies. Corroborating lines of evidence are always stronger than one clue!
Sam: Fair enough. Time to wrap up with the 6 Rs: Record, Reduce, Review, Reflect, Recite, Revise. Catch you later!
Audio 6 Transcript: The Ten Tested Skills
Alex: Hey everyone! Test day is almost here. Today we are doing a fast, rapid-fire recap of the ten tested skills from Mr. Mendoza's skills list. We're going to give you one memory hook for each skill!
Sam: Let's go! Skill 1: Stay safe.
Alex: Memory hook: SDS over smell. Never judge a hazard by looking or smelling, always check the Safety Data Sheet!
Sam: Skill 2: Pick the right graph.
Alex: Memory hook: Lines for time. Use a line graph to show change over time, and a scatter plot to see if two measured variables relate.
Sam: Skill 3: Keep records honest.
Alex: Memory hook: Make missing visible. Write "not reported" for a missing time or name, and "unassigned" for a missing number.
Sam: Skill 4: Measure where evidence sits.
Alex: Memory hook: Two points lock it in. Always measure from two fixed reference points so it doesn't end up on a circle.
Sam: Skill 5: Tell observation from inference.
Alex: Memory hook: "Because" is a guess. Keep your guesses (inferences) out of the factual record (observations).
Sam: Skill 6: Compare to known references and use exclusion language.
Alex: Memory hook: Fails to exclude. A shared blood type fails to exclude a suspect, but it never identifies them.
Sam: Skill 7: Read screening results.
Alex: Memory hook: Screens say maybe. A presumptive test needs a confirmatory test, and false positives hurt healthy people!
Sam: Skill 8: Flag lab values.
Alex: Memory hook: Inside is normal. If a number is inside the reference range, even on the very edge, it's normal.
Sam: Skill 9: Estimate time since death.
Alex: Memory hook: Divide by 1.5, divide by 1. Find the degrees lost from 37, then do the two divisions to find your cooling window.
Sam: Skill 10: Read tissue slides.
Alex: Memory hook: Rule out the prep. Before you call a tissue damaged, make sure the staining time or cut angle isn't the real problem!
Alex: That's it! Ten skills, ten hooks. Finish your studying with the 6 Rs: Record, Reduce, Review, Reflect, Recite, Revise. Good luck on the test!
Each walkthrough narrates one test from the first step to the signal you read. The gray line describes what you would see on screen.
Video 1: Presumptive Blood Tests and ABO Typing
A close-up of a hand holding a cotton swab next to a dark reddish stain on a textured surface. A large title appears: "Screening for Blood."
Investigators find a stain at the scene. Is it blood? We start with a presumptive test, or a screening test. The Kastle-Meyer test looks for heme, the iron-containing part of hemoglobin inside red blood cells.
The swab touches the stain. Two small, hand-drawn dropper bottles appear. The first adds a clear drop labeled "phenolphthalin". The second adds a drop labeled "hydrogen peroxide".
We apply a drop of colorless phenolphthalin reagent, then a drop of hydrogen peroxide.
The tip of the swab turns a bright, immediate pink. A bold green (#2fd27a) checkmark is drawn beside it.
A quick pink color means presumptive positive. This result means the target may be present. It says "maybe blood." It does not say whose blood, and it cannot even confirm if it is human. Because other substances can react and cause a false positive, every presumptive test requires a confirmatory test to say "yes."
The screen transitions to a stark white lab table. A clean, geometric ABO blood typing card sits in the center. Two circular wells are highlighted. The left is labeled "Anti-A" and the right is "Anti-B."
Once we know we have blood, we can test for markers called antigens on the surface of the red blood cells.
A drop of blood goes into each well. A drop of clear serum is added to each. The Anti-A well shows visible clumping (small clustered dots on the paper grain). The Anti-B well remains smooth and evenly colored.
We mix the sample with anti-A serum in one well and anti-B serum in another. The antibodies in the serum grab their matching markers and link the cells together. This visible clumping is called agglutination.
An arrow points to the clumping in the Anti-A well. A label appears: "Agglutination = A marker present. Type A Blood."
Here, the blood clumps only in the anti-A well. This means the red blood cells have the A marker, making it Type A blood. If it clumped only in anti-B, it would be Type B. If it clumped in both, it would be Type AB. If it clumped in neither, it would be Type O.
The camera pulls back. A gold (#f5c542) highlight underlines the words "Class Evidence."
Remember the limit of this evidence. Many people share the exact same blood type. A shared blood type fails to exclude a suspect, but it never identifies one single person.
The text fades to a simple closing card with a subtle Hornets green crest.
Trust the test, but know its limits. Finish your study session with the six Rs: Record, Reduce, Review, Reflect, Recite, and Revise. Go Hornets.
Video 2: DNA Lanes and ELISA Controls
A stark graphic of a DNA double helix unzipping. A bold title reads: "Reading DNA Lanes."
To ask whose, we look at DNA. We target short tandem repeats, or STRs. These are short DNA sequences repeated a different number of times in different people.
An illustration of a polymerase chain reaction (PCR) machine cycling temperatures, followed by a rectangular electrophoresis gel. The gel features vertical columns (lanes) with distinct horizontal bands.
First, we copy the DNA sample many times using PCR. Then, we sort those copies by size using electrophoresis. The results appear as bands in a lane.
The camera zooms in on three lanes. Lane 1 is a known reference (Suspect A). Lane 2 is the questioned sample from the scene. A green (#2fd27a) line slides down, comparing the bands horizontally.
We read the lanes band by band. You must compare the questioned sample with a known reference. If any single band is clearly different, you must exclude that reference. Every band lining up perfectly means the person is not excluded. A shared band alone is never a match; exclusion language keeps our claims honest.
A 96-well plate sits on a lab bench. The screen zooms into a single circular well.
When we need to find a specific antibody or antigen in a sample, we use an ELISA.
Step-by-step hand-drawn animations inside the well. 1. The bottom is coated with a target. 2. Fluid (the sample) is added. 3. A wash step clears out unattached pieces. 4. An enzyme-linked antibody drops in. 5. Another wash step. 6. A clear substrate is added, and the well turns blue.
We coat the well with our target and add the sample. Anything that binds stays, and we wash everything else away. We then add an enzyme-linked antibody and do one more wash. Finally, we add a substrate. If the target is present, the enzyme turns the substrate into a colored product.
The screen pulls back to show three wells. One is the sample, one is labeled "Positive Control", and one is labeled "Negative Control". The positive control is brightly colored. The negative control is totally clear.
Before you read your sample against a cutoff line, you must check your controls. The positive control must show color, and the negative control must stay clear. If either control fails, the run is invalid: report no result and repeat it.
Text appears: "False Positive" and "False Negative" with a gold (#f5c542) underline.
Tests have limits. A false positive labels a healthy person as sick. A false negative misses a sick person entirely. Each error harms different people in different ways.
The text fades to a simple closing card with a subtle Hornets green crest.
Verify your references and check your controls. Finish your study session with the six Rs: Record, Reduce, Review, Reflect, Recite, and Revise. Go Hornets.
Video 3: Time Since Death and Histology
Three minimalist clock icons appear on the screen. The labels read: "Algor Mortis", "Rigor Mortis", and "Livor Mortis."
The body keeps time after death. We use three clocks to estimate a time since death window. Rigor mortis is the temporary stiffening of muscles. Livor mortis is the settling of blood to the lowest parts of the body. If the blood pattern does not match how the body was found, the body was moved.
The first clock (Algor Mortis) expands to fill the center screen. A thermometer graphic appears.
Algor mortis is body cooling. We can calculate a time window based on this temperature drop.
A large, clean math equation builds on screen. "37 °C - Current Body Temperature = Degrees Lost" Below it: "Degrees Lost ÷ 1.5 = Short End of Window" "Degrees Lost ÷ 1 = Long End of Window"
A normal human body starts near 37 degrees Celsius. Early on, it cools about 1 to 1.5 degrees per hour. To find the window, subtract the current body temperature from 37 to find the total degrees lost. Divide that number by 1.5 for the short end of your timeline, and divide by 1 for the long end.
A gold (#f5c542) asterisk appears next to the equation.
Always state your assumptions. This calculation assumes a standard room temperature and average clothing. Extreme heat or heavy coats will bend this window.
The scene transitions to a microscopic view. A circular field shows a cross-section of pink and purple stained tissue.
Inside the lab, we examine histology, or thin slices of tissue mounted on slides. The common stain colors nuclei purple and the rest of the cell pink.
The screen splits into four quadrants, each showing a hand-drawn representation of a tissue family. 1. Epithelial (linings) 2. Connective (support) 3. Muscle (movement) 4. Nervous (signals)
There are four tissue families: epithelial for linings and coverings, connective for support, muscle for movement, and nervous tissue for signals.
A new slide appears labeled "Questioned Sample." Beside it, a pristine slide appears labeled "Normal Reference." A green (#2fd27a) bounding box highlights a tear in the questioned sample.
When looking for damage, always compare your sample to a normal reference slide. Before you call a finding abnormal, rule out preparation problems. Staining time, section thickness, and cutting angles can change how a tissue looks without actually being damage.
The text fades to a simple closing card with a subtle Hornets green crest.
One clock persuades, but three clocks that agree corroborate. Corroboration closes cases. Finish your study session with the six Rs: Record, Reduce, Review, Reflect, Recite, and Revise. Go Hornets.
Some crime scene topics appear in class stories, games or TV but are not on the Unit 1 Test skill list. Do not spend study time or practice questions on them: bloodstain (blood spatter) pattern analysis, fingerprints and fingerprint classification, footwear and tire impressions, handwriting, firearms and ballistics.
Why this matters beyond the test
- As a patient: screening results are "maybe" until confirmed; ask what a result does and does not mean, and what a normal range is.
- Life choices: protect your records and privacy; do not trust a single clue or headline.
- Careers: crime scene technician, forensic scientist and DNA analyst, forensic pathologist and medical examiner, histotechnologist, medical laboratory scientist, emergency and trauma teams, lawyers and judges who weigh evidence.
Questions? Ask me in class or message me in Schoology. Go Hornets! Mr. Mendoza