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Virginia Attorneys > Blog > Criminal Law > How do the Police and Prosecutors Collect and Use DNA Evidence in Sexual Assault Cases

How do the Police and Prosecutors Collect and Use DNA Evidence in Sexual Assault Cases


In sexual assault cases, DNA provides a prosecutor with some of the most compelling evidence. During the investigation, a nurse examiner collects samples from the body of the alleged victim. Police send the samples to a laboratory designated to conduct DNA testing on behalf of the state. The police will also obtain a search warrant authorizing them to swab the inside of the suspect’s cheek – called a buccal swab – to collect his DNA.

Depending on the nature and quantity of the sample taken from the alleged victim’s body, DNA testing generally identifies the scientific certainty who is the contributor. This kind of “traditional DNA testing” is probably the most common and provides virtually conclusive proof of someone’s connection to a crime.

A less common type of DNA testing gaining greater use in the investigation of sexual assault cases looks for male DNA. All males exhibit a “Y” chromosome on their DNA. Called “Y-STR testing” this kind of DNA testing can be conducted on very small quantities of DNA – called “touch DNA.” The testing locates the presence of male Y chromosome and further determines the statistical likelihood that the sample matches a suspect’s DNA.

Because this is a complicated and emerging area, it is important to consult with a Virginia criminal defense attorney who understands the science and works with qualified experts who can help challenge these results in court.

Contact: Rhonda Quagliana (https://www.michiehamlett.com/team/rhonda-quagliana/)

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