Effect of forensic evidence on criminal justice case processing.

This study examined the role and impact of forensic evidence on case-processing outcomes in a sample of 4205 criminal cases drawn from five U.S. jurisdictions. Regression analyses demonstrated that forensic evidence played a consistent and robust role in case-processing decisions. Still, the influence of forensic evidence is time- and examination-dependent: the collection of crime scene evidence was predictive of arrest, and the examination of evidence was predictive of referral for charges, as well as of charges being filed, conviction at trial, and sentence length. The only decision outcome in which forensic evidence did not have a general effect was with regard to guilty plea arrangements. More studies are needed on the filtering of forensic evidence in different crime categories, from the crime scene to its use by investigators, prosecutors, and fact-finders, and to identify factors that shape decisions to collect evidence, submit it to laboratories, and request examinations.