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Principles of Forensic DNA for Officers of the Court

Category 1

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In these cases in which biological evidence was collected and still exists, DNA results excluding the petitioner may exonerate him or her as the perpetrator of the crime.*

Example: Petitioner was convicted of the rape of a sexually inactive child. While vaginal swabs were taken and preserved, no previous DNA testing was conducted. DNA testing that excludes the petitioner as the source of the sperm will establish actual innocence. Note that in such a case, the victim's DNA - normally also present on the vaginal swab - operates as a control that confirms that the correct sample is being tested. In addition, the victim's age and sexual status at the time of the offense ensure that the swab contains only biological material related to the crime.

*Be aware of complex issues that arise in mixture cases.

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