Chapter 2 Self-Check Quiz: The Crime Scene

Twenty-five questions — multiple choice and short answer — to test whether the chapter's core ideas have stuck. Answer before opening the key. The goal is calibration, not a grade: notice which ones you guessed.

Multiple choice

1. The first responder's single highest priority on arriving at a possible crime scene is: - A) Photographing the scene before anything is touched - B) Establishing a chain of custody - C) Safety, then preserving life - D) Setting the perimeter

2. Why are crime-scene errors described as "irreversible"? - A) Because the lab refuses to process re-collected evidence - B) Because the original arrangement of the scene exists only once and cannot be restored after it is altered - C) Because the law forbids re-entering a scene - D) Because evidence loses its chain of custody after 24 hours

3. Wet biological evidence sealed in airtight plastic is likely to be ruined because: - A) Plastic chemically dissolves DNA on contact - B) Trapped moisture lets bacteria and fungi grow and digest the DNA - C) Plastic blocks the swab from drying enough to be tested - D) Static electricity in plastic destroys cells

4. A "substrate control" is: - A) A reference sample taken from the suspect - B) A swab of an unstained area of the same surface, to distinguish the stain from the surface and swab - C) The control panel of the analytical instrument - D) A duplicate of the entire scene

5. An unbroken chain of custody primarily establishes: - A) That the evidence was collected correctly - B) That the scene was not contaminated before collection - C) That the analysis was performed correctly - D) That the item in court is the same item collected, unaltered in any undocumented way

6. A secondary scene is best described as: - A) The second crime scene found chronologically - B) A location connected to the crime that holds related evidence but is not where the principal act occurred - C) A scene processed by a backup team - D) A scene with only trace evidence

7. A grid search differs from a line (strip) search in that: - A) It uses only one searcher - B) It covers the same ground from two perpendicular directions - C) It moves inward toward a focal point - D) It divides the scene into rooms

8. The rule "document before you disturb" exists because: - A) Photographs are required by statute before collection - B) Collecting an item destroys the scene that showed where it was - C) Sketches take longer than photographs - D) Notes must be typed before evidence is moved

9. Which container choice is correct? - A) A wet bloodstained shirt sealed immediately in a zip-top plastic bag - B) Glass fragments left loose in an open paper bag - C) An air-dried bloody swab in a sealed paper envelope; glass fragments in a sealed plastic vial - D) Both biological and inert evidence sealed wet in plastic

10. A staged scene is most reliably detected by: - A) Reading the offender's personality from the arrangement - B) Inconsistencies between what the scene claims and what the physical evidence independently shows - C) The presence of a confession - D) The absence of a chain of custody

11. Livor mortis pooled on the back of a body found face-down most directly indicates: - A) The time of death precisely - B) The cause of death - C) That the body was moved after death (the scene may be secondary) - D) That the death was an accident

12. The greatest reason the increasing sensitivity of DNA analysis matters for scene work is that: - A) It makes the chain of custody unnecessary - B) Trace contamination by responders' own cells can now create false associations - C) Plastic packaging is now safe for biology - D) Search patterns no longer matter

13. Setting the perimeter generously (farther out than feels necessary) is justified chiefly because: - A) It looks more professional - B) The perpetrator's route to and from the scene often holds rich evidence and extends beyond the body - C) Larger scenes are easier to photograph - D) The law requires a minimum perimeter size

14. Which statement about photography is correct? - A) Every evidentiary close-up should be taken with a scale in the frame - B) "Enhancement" software can reliably recover detail the sensor never captured - C) Overall shots are unnecessary if close-ups exist - D) A single photograph can substitute for the measured sketch

15. The "tunnel vision" error at a scene most dangerously causes: - A) The chain of custody to break - B) The search to collect what fits the early theory and overlook what contradicts it - C) The perimeter to be set too large - D) The notes to be too detailed

Short answer

16. State the three independent records that document a scene, and one capability unique to each.

17. In one sentence, what does an unbroken chain of custody not prove?

18. Explain, in terms of the agent of destruction, why biological evidence is packaged in paper rather than plastic.

19. Define scene security and name the record at its core.

20. A scene team finds the suspect's DNA on an object but used one pair of gloves across five items. Name the error and the term for the kind of false association it can create.

21. Distinguish a primary from a secondary scene in one sentence each.

22. Why must transient evidence be documented and collected first during a search?

23. Give the field mnemonic for packaging biological versus inert evidence, and the one-word principle behind handling biology.

24. Why is "we found no evidence pointing away from the defendant" a claim that depends on how the scene was searched?

25. Connecting to Chapter 1: explain why forensic science's power to exclude the innocent depends on good scene work.

Answer key (open only after answering) **Multiple choice** 1. **C** — Safety first (own and others'), then preservation of life, both of which outrank all evidentiary concerns. 2. **B** — The scene as first encountered is a one-time recording; altering it cannot be undone. 3. **B** — Moisture sustains microbes; bacteria and fungi digest DNA. The destruction is microbial. 4. **B** — A swab of an unstained area of the same surface, so the lab can separate the stain from the surface/swab background. 5. **D** — It establishes identity and integrity (same item, unaltered in any undocumented way), nothing more. 6. **B** — A connected location with related evidence that is not the site of the principal criminal act. 7. **B** — Two perpendicular passes over the same ground (an object hidden from one direction may be visible from another). 8. **B** — Collection destroys the scene's record of an item's location; only prior documentation preserves it. 9. **C** — Air-dried biology in sealed paper; inert glass in a sealed vial. (A destroys DNA by trapped moisture; B lets fragments escape; D is wrong on both counts.) 10. **B** — Physical inconsistency between the claimed story and the independent evidence; the stager controls appearance, not physics. 11. **C** — Settled blood inconsistent with the found position indicates the body was moved after death; the scene may be secondary. (It does not, by itself, give cause or time precisely — that is Chapter 11.) 12. **B** — Sensitivity cuts both ways: responders' own sloughed cells can contaminate and create false associations. 13. **B** — The route to/from a remote scene is often the richest evidence and lies beyond the body; perimeters are easy to shrink, impossible to expand into trampled ground. 14. **A** — Each evidentiary close-up is taken with a scale (and also as-found). "Enhancement" cannot conjure unrecorded detail (B is false). 15. **B** — Tunnel vision biases the search toward confirmation, leaving contradicting evidence uncollected — the error that quietly produces the others. **Short answer** 16. **Notes** (smells, temperatures, sounds, sequence over time, the investigator's reasoning and actions); **photography** (faithful appearance and spatial relationships, with scale for size); **sketch** (measured spatial relationships fixed to reference points, surviving even after the structure is gone). Three agreeing records are hard to attack. 17. It does not prove the evidence was collected correctly, that the scene was uncontaminated before collection, or that the analysis was sound — only custody, not quality. 18. Plastic traps moisture; moisture lets bacteria and fungi grow; they digest DNA. Paper breathes and lets the sample dry, defeating the microbes. The destroyer is microbial growth, fueled by trapped moisture (heat and sunlight also harm DNA). 19. The actions restricting access to a scene (perimeter, access control) so evidence is not lost, added, moved, or contaminated before documentation/collection; its core record is the **entry/exit (crime-scene) log**. 20. **Cross-contamination** (the error: failing to change gloves between items); it can create a **false association** between an item and material that was actually carried there by the collector. 21. Primary: the location where the principal criminal act occurred (e.g., where the victim was killed). Secondary: any other connected location with related evidence (dump site, vehicle, weapon-discard location, the route between them). 22. Because it is the most perishable — odors, warmth, drying wet prints, fading luminescence — and will not survive the hour, or may be destroyed by the search itself; durable evidence can wait. 23. *"Paper for biology, plastic for the rest."* The one-word principle for biology is **dry** (air-dry before packaging in a breathable container). 24. A search only finds what it covers and what the searcher *recognizes* as evidence; "no evidence" may reflect a search shaped by an early theory rather than the true contents of the scene. The defense should ask how the scene was searched and to what standard. 25. Exclusion (clearing the innocent, e.g., by a DNA non-match) requires a sample trustworthy enough to rely on; a contaminated, undocumented, or destroyed sample cannot cleanly exclude anyone — so the exclusion power the field most prizes is only as good as the scene work that fed it.