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Principles of Forensic DNA for Officers of the Court

Special Interpretation Considerations Related to Sexual Assault Cases: Differential Extraction

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Photo of a table with multiple evidence manila folders, as well as test tubes on it.
National Institute of Justice (NIJ) (see reuse policy).

In cases with sexual assault evidence, a differential extraction procedure is commonly used to separate sperm cells from all other cells present. If the extraction is efficient, sperm cells will end up in one tube and all other material will end up in another tube. These two separated portions are referred to as fractions .

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