The value of DNA material recovered from crime scenes

Abstract:  DNA material is now collected routinely from crime scenes for a wide range of offenses and its timely processing is acknowledged as a key element to its success in solving crime. An analysis of the processing of approximately 1500 samples of DNA material recovered from the property crime offenses of residential burglary, commercial burglary, and theft of motor vehicle in Northamptonshire, U.K. during 2006 identified saliva and cigarette ends as the main sources of DNA recovered (approximately 63% of samples) with blood, cellular DNA, and chewing gum accounting for the remainder. The conversion of these DNA samples into DNA profiles and then into matches with offender profiles held on the U.K. National DNA database is considered in terms of the ease with which Crime Scene Examiners can recover DNA rich samples of different sources, the location of the DNA at the crime scene, and its mobility. A logistical regression of the DNA material recovered has revealed a number of predictors, other than timeliness, that greatly influence its conversion into a DNA profile. The most significant predictor was found to be Crime Scene Examiner accreditation with offense type and DNA sample condition also being relevant. A similar logistical regression of DNA samples profiled that produced a match with an offender on the U.K. National DNA database showed no significance with any of the predictors considered.