Burglars go bust - the DNA field experiment
Between November 2005 and July 2007, the Office of Justice Programs’ National Institute of Justice (NIJ) provided funding to five communities (Los Angeles, Topeka, Denver, Phoenix, and California’s Orange County) to take part in a study of the effectiveness of DNA forensics in the investigation of property crimes.
Participating communities collected potential sources of biological evidence from up to 500 crime scenes between November 2005 and July 2007. Project protocol assigned half of each area’s cases to a control group, while biological material from the others underwent DNA testing. The majority of crime scenes sampled were residential burglaries, with the remainder coming from commercial burglaries and automobile thefts.
A detailed report on study results, The DNA Field Experiment: Cost-Effectiveness Analysis of the Use of DNA in the Investigation of High-Volume Crimes, can be downloaded from www.ojp.usdoj.gov/nij/topics/forensics/dna/property-crime/welcome.htm. Key results are summarized below. See sidebars for highlights of study outcomes in three participating cities (Denver, Los Angeles, and Phoenix).
Key study results:
■ Cases with DNA evidence yielded twice as many suspects identified and arrested, and more than twice as many cases accepted for prosecution. Departments obtained suspect identification via Combined DNA Index System (CODIS) hits at twice the rate generated by the FBI’s Automated Fingerprint Identification System (AFIS).
■ Additional costs incurred by departments averaged $4,515 per suspect identification and $14,178 per suspect arrest. Suspects identified with DNA evidence, however, had far more serious criminal histories. Thus, apprehension of these suspects seemed likely to have a disproportionately higher payoff in reducing the number of burglaries in a community, and potentially other types of serious crime as well.
■ DNA samples collected by patrol officers seemed just as likely to yield good evidence than those collected by forensic technicians.
■ Blood and saliva samples yielded significantly more usable CODIS profiles compared with cell samples obtained from items potentially touched by a suspect, such as a doorknob or a computer cable.
■ Crime scenes where stolen property had been left unlocked yielded fewer good samples, as did crime scenes investigated between 2 p.m. and 10 p.m. (when departments often are at their busiest).
“We’d really like to get the message out to police departments around the country that there is a lot of information, some good lessons learned, in this report,” says Katherine Browning, NIJ program manager. The study used project data to complete its key goal of a cost-effectiveness analysis. Departments could find this information useful in requesting funding to expand their DNA programs to include property crimes.
“It’s best understood as a project that sought to test different approaches to the use of DNA as an investigative tool, and not as a test of established best practices, although Denver most closely followed established best practices and had the best outcomes,” Browning says. Browning says NIJ is discussing the possibility of a one-year followup project to examine convictions and outcomes.
For more information, contact Katherine Browning, NIJ program manager, at 202–616–4786 or Katherine.firstname.lastname@example.org.
This article was reprinted from the Summer 2008 edition of TechBeat, the award-winning quarterly newsmagazine of the National Law Enforcement and Corrections Technology Center System, a program of the National Institute of Justice under Cooperative Agreement #2005–MU–CX–K077, awarded by the U.S. Department of Justice.