Criminal investigations

Test one

Terry v. Ohio (1968)

Police may stop and frisk with reasonable suspicion of criminal activity.

Carroll Doctrine (1925)

Police may search a vehicle without a warrant if they have probable cause.

Stansbury v. California (1994)

Custody is based on how a reasonable person would feel, not the officer’s intent.

Arizona v. Gant (2009)

Police may only search a car after arrest if: arrestee can access it, or it likely has evidence of the crime.

Fourth Amendment

Protects against unreasonable searches and seizures; requires warrants with probable cause.

Fifth Amendment

Protects against self-incrimination, double jeopardy, and guarantees due process.

DNA

Unique genetic identifier; highly reliable forensic evidence.

AFIS (Automated Fingerprint Identification System)

Database that stores and matches fingerprints.

Profiling Techniques

Behavioral, psychological, or geographic analysis to predict suspect traits.

Latent Prints

Invisible fingerprints left by oils/sweat; revealed by dusting or chemical processing.

Trace Evidence

Trace Evidence

Jesse James

Outlaw whose pursuit influenced early criminal investigation practices.

CSI Effect

Jurors expect unrealistic forensic proof due to crime TV shows.

Henry Fielding

Created the Bow Street Runners, first modern police investigators.

RAND Corporation

Study found most crimes are solved through witness information, not forensics.

Criminal Investigations Responses

• Reactive – after crime occurs

• Proactive – undercover/surveillance

• Preventive – deter crime before it happens

Tunnel Vision

Focusing too narrowly on one suspect/theory, ignoring other leads.

Evidence-Collection Process

• Secure scene

• Walk-through

• Document

• Collect/package

• Chain of custody

Prima Facie Evidence

Evidence strong enough to prove a fact unless disproven.

Crime Scene “Walk-Through”

Initial survey to plan evidence collection.

Steps in Writing a Report

• Gather facts

• Organize chronologically

• Write clearly

• Avoid opinions

• Proofread

Crime Scene Documentation

• Sketches: layout & scale

• Photographs: overall, mid, close-up

• Videos: real-time scene context