Convicted Offender Samples Vs Forensic Casework Samples

For a criminal DNA database to be successful convicted offender DNA samples must be entered and crime scene material from cases where there is no suspect must be tested. Because the demand for DNA testing is surpassing the ability of public forensic laboratories to perform the tests, private contract laboratories are now being used to reduce the sample backlogs for convicted offender samples. Much of this work in the United States is being performed with federal government financial assistance through grant programs administered by the National Institute of Justice.

Private DNA typing laboratories can have a higher throughput capacity because the focus is on running samples rather than performing casework and testifying in court. In addition, all of the convicted offender samples are in the same format (i.e., liquid blood or DNA extracted from buccal swabs), which improves the capability for automating the DNA typing process. On the other hand, forensic cases can involve the examination of a dozen or more pieces of biological evidence from a variety of formats (e.g., semen stains, bloodstains, etc.), which makes them much more complex.

Since July 1998, the Virginia Department of Forensic Sciences DNA laboratory system has outsourced many of its convicted offender samples (Pederson 1999). By November 1999, the Bode Technology Group, a contract service laboratory located in Springfield, Virginia, had analyzed more than 100 000 samples. Convicted offender samples were analyzed at a rate of approximately 2000 samples per week (Pederson 1999). This rapid growth in the Virginia DNA database directly led to the hit that solved the rape case discussed in Chapter 1. The Virginia state laboratories have built their capacity over the past few years and are now doing all of their own samples rather than outsourcing them as of early 2004.

To ensure that analysis of convicted offender samples by contract laboratories is performed in a reliable fashion, the DNA Advisory Board issued standards for analysis of convicted offender samples. These guidelines became effective in April 1999. Appendix IV contains a copy of the contract laboratory quality assurance standards in a format that directly compares them with the standards for quality assurance of forensic casework samples.

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Stammering Its Cause and Its Cure

Stammering Its Cause and Its Cure

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