One DNA Test... Many Interpretations... Reasonable Doubt?

Each attorney has different needs and varying understandings of DNA testing and interpretation. Some do not know much about DNA, while others are very familiar with DNA testing and laboratory procedure. Forensic services are available to meet the needs of clients across the spectrum.

The following scenarios depict three different situations that require three different approaches from DNA experts.

Scenario A: "I'm new to the DNA testing field."
For those attorneys who have never been involved with a DNA case, their first one can be quite daunting. From the acronyms (i.e. PCR, STR, ASCLD/LAB, CODIS), to the statistics, to the terms (i.e. mixtures, partials, minor alleles, loci), there is a lot to know and understand. A DNA report may state that John Doe's DNA profile is consistent with evidence and that he can't be excluded as a contributor. The probability of an unrelated individual having the same profile as that on the evidence is 1 in 40,000,000,000,000,000 (or 40 quadrillion) individuals. The questions that may follow are often: Is DNA infallible? Was a mistake made? Is the evidence probative? Where does this statistic come from? How do we know what the source of the DNA is? What do I ask during cross? This is where it all begins! Case review and consultation can answer those questions and help prepare the attorney for the case.

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Kathryn McHenry is a DNA analyst for the Forensic Department at DDC, serving as one of the company's first forensic laboratory specialists. Some of her routine activities include the examination of evidence, serological testing, extraction of DNA, and gene fragment analysis. Kathryn also specializes in the extraction of DNA from difficult samples such as tooth and bone.

Along with her daily DNA case analysis, Kathryn is often called upon to testify on casework that she has completed. With her expertise in both DNA crime scene collection and serology, Kathryn plays an essential role in training law enforcement and legal professionals through DDC's DNA workshops. Kathryn also helps prepare and revise manuals for our laboratory accreditations and is an integral part in the continuation of DDC's quality assurance and quality control.

Kathryn graduated with honors with a bachelor's degree in biology from Berea College. Her emphasis of study was cell and molecular biology. In addition, Kathryn has also completed graduate level coursework and research in cellular and molecular biology at the College of Medicine at University of Cincinnati.