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Understanding Male DNA Screening To Eliminate and Prevent Sexual Assault Kit Backlogs

NCJ Number
Amy Jeanguenat
Date Published
November 2017
This paper discusses male DNA screening of evidence in sexual assault kits (SAKs)) as an efficient method for reducing SAK backlogs.
The reduction of manual steps and optimizing automation is essential for improving the efficiency of processing SAKs. Many forensic laboratories screen SAKs for biological fluid, such as semen, a process that takes approximately 4-7 hours per kit. Following biological fluid screening, the samples deemed probative for possible DNA are selected for differential extraction, a process that separates sperm cells from non-sperm cells. The trained capacity and number of hours needed to screen thousands of SAKs, even without proceeding with DNA testing, can create a bottleneck in laboratory case processing. An alternative process for screening SAKs is male DNA screening, also known as Y-Marker screening or direct-to-DNA. Male DNA screening shifts the emphasis from screening SAKs for biological fluid to screening them with quantification, a step already used in DNA processing to determine how much DNA a sample contains. Because modern commercial quantification kits determine how much human DNA (both male and female DNA) and male DNA a sample contains, quantification can be used in the screening process, taking less than 1 hour per kit. Male DNA screening can be automated for high-throughput testing, since male DNA screening does not detect seminal fluid or semen. Screening for male DNA can detect possible probative samples in cases that involve digital penetration or other touching in sexual contact that involves no ejaculation or azoospermic males who currently screen negative in biological fluid screening. In one study, male DNA screening proved more effective than biological fluid screening in detecting male DNA from vaginal swabs, external genitalia, and dried secretions. This report describes and compares methods of male DNA screening.