The DNA field experiment: a randomized trial of the cost-effectiveness of using DNA to solve property crimes

Abstract

We report the results of a prospective, randomized study of the impact and cost-effectiveness of DNA evidence in investigating property crimes, mainly residential burglary. Biological evidence was collected at up to 500 crime scenes in five U.S. cities between 2005 and 2007, and cases were randomly assigned to the treatment and control groups in equal numbers. DNA processing was added to traditional investigation in the treatment group. A suspect was identified in 31% of treatment cases and 13% of control cases. A suspect was arrested in 22% of treatment cases and 10% of control cases. Across the five sites, each additional arrest-an arrest that would not have occurred without DNA processing-cost slightly more than US $14,000. In the most cost-effective sites, an additional arrest cost less than US$4,000. Expanding the use of DNA as an investigative tool has profound implications. Since DNA-led investigations are more costly than business-as-usual, substantial investments will be required to expand the capacity of crime laboratories, police, and prosecutors to use this investigative tool efficiently. In time, such a change may also impact the types of crimes of cases processed in the criminal justice system.

Should Rape Kit Testing Be Prioritized by Victim–Offender Relationship?

“…Peterson and colleagues () noted that “investigators [may be] more inclined to classify [stranger‐perpetrated] alleged sexual assaults as a crime (a requirement for uploading)” (p. 83). The CODIS entry and hit rates documented in this study were substantially higher than in other SAK‐related projects, but interestingly, they were similar to Roman, Reid, Chalfin, and Knight's () study of forensic testing outcomes for burglary crimes. In that project, DNA evidence from 1,079 burglary cases was tested, and 55% of the samples yielded a CODIS‐eligible profile, of which 43% produced a CODIS hit.…”

Developing Empirically Informed Policies for Sexual Assault Kit DNA Testing: Is It Too Late to Test Kits Beyond the Statute of Limitations?

“…In Peterson and colleagues' (2012) in-depth examination of 1,320 SAKs randomly sampled from 10,895 "backlogged/untested" rape kits from Los Angeles that dated back to 1982, there were 699 DNA profiles entered into CODIS (53% of the total sample tested), resulting in 347 CODIS hits (26% of the total sample tested, 50% of profiles entered into CODIS; serial sexual assault rate not reported). These CODIS hits rates are similar to the results from an analysis of DNA forensic testing outcomes for 1,079 burglary cases from 2005 to 2007 (which were within SOL at the time the study was conducted), which found that 55% of the samples yielded a CODIS-eligible profile, of which 43% produced a CODIS hit (Roman, Reid, Chalfin, & Knight, 2009). Violent crimes against a person are markedly different from property crimes in many ways, and yet the DNA forensic testing outcomes across these studies were comparable: about half of the cases analyzed yielded CODISeligible profiles and then roughly 40% to 50% of those profiles produced CODIS hits.…”

DNA in the Criminal Justice System: The DNA Success Story in Perspective,

“…Only in 6% (176/2791) of HVC‐crime cases, DNA traces were actually analyzed. In a U.S. DNA field experiment on property crimes conducted in 2009 , a suspect was identified through a DNA database match in 16% of the cases. In 13% of the cases in the “DNA evidence group,” a suspect was identified through traditional police work.…”