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Role and Impact of Forensic Evidence in the Criminal Justice Process

NCJ Number
Date Published
October 2010
151 pages
The reported study estimated the percentage of crime scenes from which one or more types of forensic evidence is collected; described and cataloged the kinds of forensic evidence collected at crime scenes; tracked the use and attrition of forensic evidence in the criminal justice system from crime scenes through laboratory analysis, and then through subsequent criminal justice processes; and identified which forms of forensic evidence contributed most often (relative to their availability at a crime scene) to successful case outcomes.
For the five jurisdictions analyzed, the study found that the collection of forensic evidence from crime scenes and victims was extensive in homicides and, to a lesser extent, rapes; it was significantly more limited for assaults, burglaries, and robberies. With the exception of homicides, few of the reported offenses involved forensic evidence that was submitted to crime laboratories. Such submissions were 89 percent for homicides; 32 percent for rapes; and under 15 percent for assaults, burglaries, and robberies. Also, the overall percentage was low for reported offenses that had physical evidence examined in crime labs, with the exception of homicides (81 percent); it was less than 20 percent for rape cases and less than 10 percent for assaults, burglaries, and robberies. Of evidence submitted to labs, however, rates of examination exceeded 70 percent, with the exception of rape cases (58 percent). These findings suggest that criminal justice officials screen much of the forensic evidence in determining which evidence will be sent to crime labs for analysis, giving them significant discretion in determining evidence-examination priorities and practices. The most frequently collected, submitted, and examined types of evidence were fingerprints, firearms, and biological material (blood and semen). DNA evidence was concentrated in homicide cases and, to a lesser extent, rape cases. Specific follow-up research is recommended. 10 figures, 24 tables, 28 references, and appended data on unique/associative evidence and the increase in DNA analysis

Date Published: October 1, 2010