Monday, June 16, 2008
The study compared traditional crime solving to biological evidence techniques in hundreds of cases where biological evidence was available. When conventional investigative techniques were used, a suspect was identified 12 percent of the time, compared to 31 percent of the cases using DNA evidence. In eight percent of cases built on traditional evidence alone a suspect was arrested, compared to the 16 percent arrest rate in DNA cases. The average added cost for processing a single case with DNA evidence was about $1,397. Each additional arrest—an arrest that would not have occurred without DNA processing—cost $14,169.
The study’s main findings are that:
- Property crime cases where DNA evidence is processed have more than twice as many suspects identified, twice as many suspects arrested, and more than twice as many cases accepted for prosecution compared with traditional investigation;
- DNA is at least five times as likely to result in a suspect identification compared with fingerprints;
- Suspects identified by DNA had at least twice as many prior felony arrests and convictions as those identified by traditional investigation;
- Blood evidence results in better case outcomes than other biological evidence, particularly evidence from items that were handled or touched;
- Biological material collected by forensic technicians is no more likely to result in a suspect being identified than biological material collected by patrol officers. [Mark Godsey]