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Law 101: Legal Guide for the Forensic Expert

Types of Evidence

Types of Evidence
National Institute of Justice (NIJ) (see reuse policy).

Evidence can be any perceptible thing that tends to demonstrate, establish or disprove a fact. In addition to testimonial proof (e.g., witness testimony based on perceiving an event or based on an opinion rendered by a qualified person), evidence may be physical (data created pursuant to forensic examination, photographs, digital evidence or ballistics) or demonstrative.

Demonstrative evidence refers to an item that is not from the crime scene itself but that can illustrate (demonstrate) a concept. An example of demonstrative evidence is an anatomically correct model used to show where the victim was injured.

There are many laws, rules and cases that control the admissibility, the method of admission, the form, the weight to be given, the order of evidence presented in a trial, and the correct objections to unreliable, inappropriate evidence.

In order to be considered by the finder of fact, evidence must be relevant and admissible.

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