Collect Trace Biometric Evidence
Collect small trace evidence and body-based biometric evidence without contaminating it.
- Observation vs. inference: Forensic work starts by separating what was seen from what is concluded.
- Evidence identity: Labels, photos, and logs keep evidence tied to the right source.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Collect small trace evidence and body-based biometric evidence without contaminating it.
| Evidence | Type | Collection note |
|---|---|---|
| Hair fiber | Trace | use forceps, paper bindle |
| Fingerprint | Biometric | lift or photograph |
| Shoeprint | Impression | photograph with scale |
| Control fiber | Control sample | known comparison |
Use the trace evidence table. Which collection note fits a fingerprint?
Reviewed| Evidence | Type | Collection note |
|---|---|---|
| Hair fiber | Trace | use forceps, paper bindle |
| Fingerprint | Biometric | lift or photograph |
| Shoeprint | Impression | photograph with scale |
| Control fiber | Control sample | known comparison |
- A.Lift or photograph it
- B.Calculate mean
- C.Ask patient pain level
- D.Place in liquid media
Show the worked solution ▾
Answer: A. Lift or photograph it
- Step 1: Find fingerprint row: The table lists fingerprint as biometric evidence.
- Step 2: Read note: The note says lift or photograph.
Why it's right: Fingerprints should be lifted or photographed.
- B: Mean is a statistic.
- C: Pain level is clinical history.
- D: Liquid media is for cultures, not prints.
Aligned to Biotechnology Research and Experiments · reading level ~grade 9
A damp bloodstained cloth is recovered at a scene. Why is it air dried and packaged in paper instead of sealed wet inside a plastic bag?
Reviewed- A.Paper bags weigh less, so more items fit in the transport case
- B.Paper soaks up the blood, which concentrates the sample for testing
- C.Trapped moisture lets mold and bacteria grow, which breaks down the DNA
- D.Plastic reacts with blood and turns the stain a different color
Show the worked solution ▾
Answer: C. Trapped moisture lets mold and bacteria grow, which breaks down the DNA
- Step 1: Ask what a sealed wet bag does: It holds moisture against the stain.
- Step 2: Ask what moisture does to a biological sample: Damp conditions grow mold and bacteria, and that growth degrades the DNA the lab needs.
Why it's right: Paper breathes, so the stain dries. A sealed plastic bag traps moisture, and mold and bacterial growth in that moisture degrade the DNA.
- A: Bag weight is not a reason to choose a packaging material for biological evidence.
- B: Blood soaking into the bag loses sample rather than concentrating it.
- D: Plastic does not chemically alter a bloodstain; the problem is trapped moisture.
Aligned to Biotechnology Research and Experiments · reading level ~grade 9
- In Unit 1.1 Investigating the Scene, this skill turns class evidence into a result another person can check.
Fill these in as you work through the lesson.
- Trace evidence (small transferred material):
- Biometric evidence (body-based identifier):
- Control sample (known comparison sample):
- Contamination (unwanted material added):
Use clean tools, collect the evidence, and package it separately with a sample when possible.
- Is the clue trace or biometric?
- What tool prevents contamination?
- What known sample would help comparison?
A fiber is found on a jacket. Choose a collection tool, package, and control sample.