Crime Scene Study Guide — Chapter 2

Crime scene

The location and surrounding areas where a crime has happened.

Physical evidence

Anything that can be collected from a crime scene.

Three main functions of physical evidence

Establish that a crime occurred, link to perpetrator, link to victim.

Crime scene processing Step 1

Preserve life (get medical help).

Crime scene processing Step 2

Protect the area using ropes, barricades, and guards.

Crime scene processing Step 3

Take overview and close-up photos of the unaltered scene.

Rough sketch

A sketch made directly at the crime scene.

Finished sketch

An accurate sketch drawn to scale.

Crime scene processing Step 5

Write detailed descriptions of evidence and the scene.

Crime scene processing Step 6

Search thoroughly and systematically; body is searched at autopsy.

Crime scene processing Step 7

Avoid contamination and keep evidence in original condition.

Crime scene processing Step 8

Use separate containers, label everything, and choose correct packaging.

Crime scene processing Step 9

List everyone who contacts evidence and document its transfers.

Crime scene processing memory trick

Life, Protect, Photograph, Sketch, Notes, Search, Collect, Package, Chain.

Spiral search method

Search in a spiral pattern, moving inward or outward.

Grid search method

Search the area in overlapping lines in two directions.

Strip or line search method

Walk in parallel lines across the search area.

Quadrant or zone search method

Divide the scene into smaller sections and search each.

Wet, bloodstained materials packaging

Place in paper bags to allow air-drying.

Fire and arson evidence packaging

Use airtight containers because they trap fumes.

Common evidence collection tools

Tweezers/forceps, manila envelopes, and unbreakable bottles.

Contamination

Unwanted material introduced to evidence, potentially affecting the investigation.

Standard or reference sample

A known sample compared with crime scene evidence.

Reference sample example

Compare bloodstains with the blood of victim and suspect.

Crime scene safety: Gloves

Wear two layers of latex gloves.

Crime scene safety: Disinfection

Disinfect surfaces and equipment with bleach.

Crime scene safety: Biological waste

Put biological waste in red biohazard bags.

Biological fluids risk

May contain infectious agents, including HIV or hepatitis.

Fourth Amendment

Protects against unreasonable searches and seizures.

Warrantless search situations

Emergencies, arrests, permission, and destruction of evidence.

Mincey v. Arizona

Four-day warrantless search of homicide scene; guilty verdict reversed.

Michigan v. Tyler

Arson investigation involving three warrantless searches; guilty verdict reversed.