A probe of a Texas police crime lab in Houston conducted by an independent criminologist has found a high rate of faulty DNA test results and blood analyses that would not pass usual standards, but only two men have been released from prison as a result of the substandard work.
Prosecutors argue that lab evidence was not the key to many convictions, so few deserve to be overturned. In 2002, Harris County District Attorney Chuck Rosenthal and top police officials announced that 400 cases involving DNA testing performed at the lab would be re-examined. They made the announcement after a series of television reports questioned the lab's operations.
Some lab officials subsequently were disciplined or fired. Two grand juries that investigated the lab's operations found no proof of criminal negligence, but the trickle of complaints erupted into a major scandal. City leaders closed the lab and hired an outside specialist to evaluate several years' worth of criminal prosecutions.
A report released in January by Michael Bromwich, a former Justice Department inspector general, found problems with 40 percent of DNA cases and 22.5 percent of blood-work cases handled by the laboratory between 1987 and 2002. The city then allowed Mr. Bromwich to examine convictions dating back to 1980 in which work performed by the crime lab was a key factor.
One of two convictions overturned was that of Josiah Sutton, who had served more than four years on a rape charge when a retest found that DNA evidence used to convict him was false. He was released in 2003. George Rodriguez served 17 years before being released in 2004. He also was cleared by DNA retesting.
Mr. Rosenthal, who has sent more men to death row than any other Texas district attorney, vowed to make sure those convicted wrongfully are either tried again or released.
"We have that obligation," he said.
The lab investigation has cost more than $4 million, and some lawmakers are ready to become more involved.