In at least nine homicide, sex assault and burglary cases, Baltimore police detectives instructed crime lab technicians not to follow up on convicted criminals' DNA found on evidence at crime scenes because they determined it was not relevant to their investigations, police said.
Baltimore State's Attorney Patricia C. Jessamy has requested a complete review of cases handled by the lab, saying that prosecutors and defense attorneys need to be made aware of all the evidence police collect.
"We're working on it," Jessamy said Thursday. "We don't know the full extent of it."
Police spokesman Sterling Clifford played down the significance of the discovery, saying detectives routinely make judgment calls on evidence. But he said the department's policy has been changed and that officials are now hand-searching case files for similar irregularities, a process that is expected to take a "significant amount of time."
Last month, longtime city police crime lab director Edgar Koch was fired after the discovery that a dozen "unknown" genetic samples found in evidence actually turned out to be the DNA of lab employees. Defense attorneys and forensic experts said flaws that allowed such contamination to occur likely indicated more widespread problems at the lab.
But the revelation that police did not follow up in cases when DNA found on evidence collected at crime scenes was matched to the profiles of convicted criminals stored in the FBI's database is likely to stir greater alarm. It raises the possibility that other suspects or co-defendants might not have been pursued, or that charges were dropped in cases where the ignored DNA might have offered a smoking gun.
Police and prosecutors would not provide details about the nine cases, which include six open homicide and sex assault cases and three closed burglary cases over the past seven years.
Walter F. Rowe, chairman of the forensic science department at George Washington University, said he had never heard of such an issue and said it was standard procedure for police to follow up on DNA matches.
"It's something where you'd argue that prudent police work would involve ascertaining exactly where this guy [whose DNA was matched] was at, what his story is. Maybe he had been there at one time, or maybe he was an accomplice," Rowe said. "I don't think it can be cavalierly brushed under the rug. If the case isn't absolutely iron-clad, then you've got reasonable doubt."
