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Principles of Forensic DNA for Officers of the Court

Interpreting Mixtures

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Mixtures of DNA are commonly encountered in forensic science. One of the most common type involves the contribution of biological material by two individuals from intimate samples often encountered in sexual assault investigations. This occurs when the differential extraction of sperm from other cellular material (non-sperm) is not complete.  Mixtures are also commonly encountered in "touch" DNA samples, when multiple people handle or come in to physical contact with an item that is later tested for DNA.

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