Role and Impact of Forensic Evidence in the Criminal Justice System, Final Report

A literature review addresses the use of forensic evidence, forensic databases, previous studies of forensic evidence, types of forensic evidence, and the probative value of forensic evidence. This is followed by a chapter that analyzes forensic evidence from serious crimes (homicides, sexual assaults, aggravated assault, robberies, and burglaries) that occurred in Denver, CO, in 2005 and 2006. The analysis includes an examination of evidence collected at crime scenes and evidence analyzed by the police department's crime lab, as well as the impact of the evidence on the investigation and adjudication of the cases. Chapter 3 follows the format used in Denver in examining cases in San Diego, CA, but with one important difference. In San Diego, researchers were able to merge arrest and crime data so as to obtain a larger sample of closed cases than would have occurred with simple random sampling. Chapter 4 presents the results of an experiment in the Miami-Dade Police Department that determined whether clearance rates for no-suspect property crimes could be improved through faster processing of DNA evidence. Chapter 5 presents a qualitative review of cases in which forensic evidence was instrumental in either identifying suspects or assisting in prosecution. Chapter 6 presents the findings of a survey of selected law enforcement agencies in order to address several issues regarding the collection of evidence from crime scenes, with attention to the characteristics and operations of crime-scene units. The concluding chapter recommends topics for future research on the topic of this report. 54 exhibits and extensive references