Evidence Collection

3rd Grade Workshop

When a crime has been committed, a team of policemen usually called

investigators are sent to the scene of the crime.

It is their job to collect any and all

possible evidence that is located at the crime scene.

Locard’s Principle

•Developed in 1910 by Edmond Locard, the principle states that criminals always take a trace of something and leave a trace of something behind at the crime scene.

Police Procedures

Procedures at the Crime Scene:

1.Check the victim (ensure that they are ok)2.Secure the area3.Document the area

a. Take pictures, sketch, or videotape the crime scene.

b. Take measurements4.Search for and collect any and all evidence.5.Interview any witnesses

Types of EvidenceEvidence is anything that helps prove the guilt or innocence of a person suspected of a crime. There are two types of evidence – direct and circumstantial.

•Circumstantial evidence is sometimes called indirect evidence. It provides supporting facts to establish the truth through an indirect means. For example, if a person’s fingerprints are found at the scene of the crime, the prints are circumstantial evidence.

•Direct Evidence proves the fact without a doubt. Some examples of direct evidence include a videotape of the crime being committed or an eyewitness to the crime.

Evidence CollectionWhen the police find evidence at a crime scene, they follow certain procedures to preserve and document the evidence. They have to prove that the evidence never left their possession once the collected it. Therefore, hey usually follow these steps:

1.Each piece of evidence is put in its own separate container which is then labeled and sealed.

2.The label tells where and when the item was found and is initialed by the officer that found the evidence.

3.Finally, the evidence is sent to the crime lab for further testing.

At the Lab

Once the evidence gets to the lab, there are more procedures that have to be followed:

•Each item is listed in the evidence register•Evidence is kept in as locked room•Only authorized people can view it•Exact records are kept of each person who has handled the evidence.•The evidence is examined by trained professionals to analyze and interpret it.

Scientific MethodWhen detectives are trying to solve a crime, they use the scientific method. Scientists use this method to observe and test various explanations of the crime.

Steps of the Scientific Method1.Gather all possible evidence2.Study all of the evidence3.Look for errors or inconsistencies4.Form a hypothesis5.Test the hypothesis