In TV crime dramas, DNA from a crime scene is matched to a suspect, and a conviction follows, says USA Today. In real life, Virginia’s crime lab has found there were convictions in fewer than one-quarter of more than 3,000 cases in which analysts matched crime-scene DNA to a genetic profile in the state’s databases. It was the first major study of what happens in criminal cases after a DNA match is found. Forensic analysts say the findings raise questions about the effectiveness of the nation’s network of DNA databases, the Combined DNA Index System (CODIS), as the White House proposes to spend $1 billion to greatly expand testing. “We love to talk about our CSI-style matches, but nobody has wanted to look too deeply into what they really amount to,” says Max Houck of West Virginia University’s forensic science program. “We’re pouring millions into (the DNA) system, and we don’t have any idea whether it’s cost-effective in the area that really counts,” getting convictions.
The FBI says the CODIS network of DNA profiles from more than 2.7 million offenders has scored nearly 28,000 matches nationwide since 1992. In Virginia, it is unclear how many of the out-of-state matches found by analysts led to convictions. But among the in-state matches, 597 – under 22% – led to guilty pleas or guilty verdicts after a trial. In nearly 424 other in-state matches, prosecutors declined to press charges because victims could not be found or were reluctant to testify, or evidence tested turned out to be irrelevant. In 1,760 other matches, investigations were pending or could not be analyzed because local authorities had lost track cases or did not respond to state requests for information.