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Crime Scene and DNA Basics for Forensic Analysts


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Compared to an outdoor scene, evidence at an indoor scene is generally less susceptible to loss, contamination and deleterious change. Indoor crime scenes are usually easier to secure and protect, and securing a scene can be as simple as closing a door.

The methods used by forensic laboratories have evolved so that very small amounts of biological material can produce a usable DNA profile. This, however, means that the potential for detecting DNA traces deposited by contamination at crime scenes becomes a factor. Contamination of any crime scene can easily occur if proper precautions, such as limiting the number of people inside the scene, are not taken. For example, first responders, emergency medical personnel, patrol supervisors, crime scene investigators, and medical examiners are all potential sources of contamination and/or loss of evidence.

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