Determining Probative Value of Evidence

Determining the probative value of evidence submitted to the laboratory begins with case details. Frequently, this is in the form of written descriptions from an investigator, in-person discussions, telephone conversations, etc. This information provides the laboratory with an understanding of the relationships between the items submitted for analysis and the events surrounding the crime, which allows the analyst to screen the evidence more effectively. Providing this information does not mean the screening process is limited only to the scenario provided. The examination may reveal additional information that can redirect an investigation. It is important to keep in mind that not all biological evidence is probative to the case. It is common to find biological stains at a crime scene that were deposited before the crime occurred or are not related to the case. In these instances, it may be important to obtain known DNA samples (elimination samples) from individuals who may have had non-probative contact with the crime scene.

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