Revista de investigación forense

The Judicial Use of DNA Evidence and Forensic Expert Testimony in the Criminal Justice System

Abstract

Richard S. Gunasekera, Jennifer Haschke and Elliott H. Costas J.D.

In the forensic sciences, DNA analysis is especially useful in sexual assault cases where body contact is made or bodily fluids are exchanged. However, its usefulness can be severely limited within the contour of the criminal justice system. This article discusses a case wherein short tandem repeat DNA typing was used to charge the defendant with sexual assault of a child. The State’s DNA technicians analyzed the victim’s underclothing and reviewed the victim’s sexual assault nurse examination (SANE). Our independent review of the State’s forensic laboratory work showed that the samples used to obtain a DNA match from the victim’s underclothing and the defendant revealed a third contributor. An allele was found that did not match either the victim or the defendant as shown by us as expert witness. A ruling by the trial judge limited what the jury was allowed to hear regarding our findings. The defendant was found guilty. The defendant appealed the guilty verdict based on the trial judge’s decision to limit defense expert witness testimony. Following established law, the appellate court upheld the conviction, ruling that a victim’s testimony alone, with or without any corroborating forensic evidence, supports a finding of guilt.