CSI Terms

Alternate light source

A device emitting various wavelengths of light to help investigators locate and enhance evidence like fluids

Associative evidence

Evidence that links a person or item to the crime scene

Biological evidence

Physical evidence originating from a human

Chain of custody

The documented process that records the handling of evidence from collection to analysis

Contamination

Unwanted transfer of material to evidence

Control sample

Material from a known source presumed uncontaminated during the crime

Cross-contamination

Unintended transfer of material between evidence sources

Elimination sample

Known material from someone with lawful access to the scene

First responders

Initial law enforcement or public safety officials arriving at the crime scene before investigators

Fluorescent powders

Powders with fluorescent chemicals applied to surfaces to reveal latent prints under specific lighting

Impression evidence

Objects or materials that have retained characteristics of other objects pressed against them

Latent print

A fingerprint

Locard’s Exchange Principle

The theory that every contact leaves a trace

Other responders

Individuals involved in aspects of the crime scene like security

Presumptive test

A preliminary test indicating the possible presence of a substance but not confirming its identity

Probative

Having the potential to provide valuable information to an investigation

Reconstructive evidence

Evidence that helps understand the actions that occurred at the crime scene

Reference sample

Material from a verified source used to compare with unknown evidence to establish a link

Trace evidence

Small quantities of material transferred during a crime

Transient evidence

Evidence that can lose its value if not preserved promptly

Unknown/questioned sample

Evidence of unknown origin found at a crime scene or on a suspect