How Was the DNA Field Experiment Performed?
Each jurisdiction in the study collected potential sources of biological evidence—along with conventional evidence such as fingerprints—from up to 500 property crime scenes between November 2005 and July 2007. The majority of the crime scenes were residential burglaries; the rest were commercial burglaries and automobile thefts.
- Step 1: Half of the cases were randomly selected to be analyzed to see if a DNA profile could be determined; the remaining half were
not tested (or testing was deferred for a few months), thus serving as the control group.
- Test group (approx. 250/site) = Traditional investigation + DNA testing
- Control group (approx. 250/site) = Traditional investigation only
- Step 2: The test group samples were analyzed by a laboratory to determine a DNA profile.
- Step 3: DNA profiles were run against CODIS.
- Step 4: Investigative teams followed up on CODIS hits with further investigation and possible filing of charges.
Jurisdictions in the field experiment had to modify investigative and reporting procedures to accommodate the needs of the experiment—and, although they encountered challenges, most were met successfully. Many lessons learned through the field experiment offer "best practices" on using DNA forensics in solving property crimes.