Those of us who have been part of the forensic DNA community for the past 15 years have waited a long time for this. We knew it would come. We knew theoretically and anecdotally, that it was true. We only needed to look across the Atlantic to see evidence of it. But now, finally, an independent and respected research institution has substantively proven it. The investment in DNA technology to solve volume crime makes tremendous sense. More to the point, it has become a responsibility.
In 2005, police departments from Phoenix, Arizona; Orange County, California; Los Angeles, California; Denver, Colorado; and Topeka, Kansas, began their participation as demonstration sites for the National Institute of Justice sponsored Urban Institute DNA Field Experiment. Each agency was to collect biological evidence from five hundred crime scenes. Those cases were then randomly split in half with 250 being investigated though only traditional investigative means, while the other 250 were investigated through traditional means and by having the biological evidence in the case tested for DNA. In approaching the investigations in this manner, it could be concluded that any difference in outcomes would be attributable to DNA testing.
There were certain variables between test sites. For example, Phoenix and Los Angeles outsourced samples while the other sites performed DNA analysis in-house. Some sites utilized forensic technicians for evidence collection while others allowed for the collection of crime scene evidence by patrol officers. And while there were expected variations in the results among the five sites, the overall conclusions of the study have tremendous implications for how DNA is, and should be, used in the United States.
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.
CHARACTERISTICS OF SUSPECTS IN HIGH VOLUME PROPERTY CRIME—THE SIGNIFICANCE OF RECIDIVISM
In a confirmation of smaller, previous studies by agencies such as the Chicago and Miami-Dade Police Departments, the Urban Institute examined the criminal histories of individuals identified through CODIS and those arrested without a CODIS identification. In general, the Institute’s conclusion was that “… suspects identified within the test cohort (CODIS) were significantly more likely to have additional prior felony convictions, more prior felony arrests, more prior misdemeanor convictions, and more prior misdemeanor arrests.” Specifically, in CODIS identification cases, suspects averaged 5.6 prior felony arrests, 2.9 prior felony convictions, 3.0 prior misdemeanor arrests, and 2.2 prior misdemeanor convictions.