Two years ago, the problems at Houston's police crime lab appeared serious but not catastrophic: a leaky roof, insufficient ventilation, a backup in the processing of rape kits and possible water contamination of evidence.

Those were the issues that City Council member Carol Alvarado raised to her colleagues in summer 2002, after taking a half-day tour of the facility at the urging of a concerned lab employee.

What the council and other city officials quickly came to realize was that shabby lab conditions presaged a much more serious problem. "There was a long history of inefficiencies," Alvarado said. "Could that have someone sitting in jail that could be innocent?"

Multiple and continuing investigations since then have proved just that.

So far, one Houston man convicted of rape, and imprisoned 41/2 years, has been released after the crime lab's DNA tests were discredited by new tests. Josiah Sutton subsequently was pardoned in May by Gov. Rick Perry (R).

On Thursday, Harris County District Attorney Chuck Rosenthal announced that another Houston man, incarcerated for 17 years on kidnapping and rape charges, was convicted on "scientifically unfounded and inaccurate" trial testimony by a former crime lab supervisor. But Rosenthal said he will retry the inmate, George Rodriguez. Rodriguez is expected to be released on bond soon and his attorneys will seek to overturn his conviction, which brought him a 60-year sentence.

Even Houston's top police official this week called for a moratorium on executions of death row inmates convicted on evidence handled or analyzed by the crime lab. Of the 454 inmates on Texas's death row, more than a quarter are from Harris County. One of those Houston men, Edward Green III, 30, is scheduled to die by injection Tuesday.

"I think it would be very prudent for us as a system, that is, a criminal justice system, to delay further executions until we've had an opportunity to reexamine evidence that played a particular role in the conviction of an individual that was sentenced to death," Chief Harold L. Hurtt said at a news briefing at police headquarters Thursday.

"We are talking about life-and-death situations," he said. "We need to do what is right."

The task of sorting out the problems has been made even more difficult with the recent revelation by Hurtt that an internal investigation discovered 280 abandoned and mislabeled boxes of evidence that included a fetus and body parts, along with guns and other weapons, in a police property room. The boxes hold evidence from 8,000 cases, including open and closed murder cases, dating from about 1979 to 1991, Hurtt said. The boxes had been sent to the police property room by the crime lab and predate DNA testing, which began in 1992.

DNA testing by the crime lab was halted in December 2002 after an independent audit disclosed possible evidence contamination and improper analysis. Rosenthal's office then ordered retesting of DNA evidence processed by the lab and used to obtain criminal convictions. That retesting allowed Sutton to be released from prison.

In the summer of 2003, the Houston Chronicle reported that lab analysts had complained about lab conditions several years ago to then-Police Chief C.O. Bradford. The DNA lab chief and an assistant chief in charge of the crime lab subsequently retired, as did Bradford. Shortly afterward, a Harris County grand jury investigated the issues involving the crime lab, but did not return any indictments.

Last fall, city officials tried to make improvements at the lab by hiring a new director, but almost concurrently the lab's toxicology division was forced to close for four months when a supervisor failed a competency test. Even now, outside labs are used for DNA testing.

About the same time in August that Hurtt announced the discovery of the 280 abandoned boxes of evidence, attorneys for the convicted rapist, Rodriguez, released a report by six forensic experts who concluded the crime lab's analysis of DNA in his case to be "scientifically unsound." Though Rodriguez was convicted in 1987, before the use of DNA testing, a judge had ordered in 2002 that the city's police lab conduct DNA testing on any remaining evidence in his case.

Then this week, the district attorney's office announced that a new, independent analysis of chemical testing used to convict Rodriguez found the testing was inaccurate.

"This shows there is absolutely nothing reliable about the forensic science taking place in the crime lab," said Vanessa Potkin, a staff attorney for the New York City-based Innocence Project, which has been representing Rodriguez since 2000.

"It didn't start with DNA testing. The problem is prevalent, widespread and serious. It was prevalent in typical serology science," she said. "Nothing can be considered reliable out of that lab."

For much of this year, the police department has been working to get the crime lab accredited for the first time in its history. Hurtt also authorized the hiring of a "project leader" to head a team of outside experts and local residents to review crime lab records and look into questions pertaining to evidence processing. When DNA testing will be resumed is not clear.

"What we want to do is bring credibility back to the crime lab," said Executive Assistant Chief Martha Montalvo.

Police Chief Harold L. Hurtt supports a delay in executions. District Attorney Chuck Rosenthal plans to retry George Rodriguez.Priscilla Onofre, sister of George Rodriguez, laments that Rodriguez, who according to DNA evidence was wrongly convicted of a 1987 rape, could not be released from prison for his father's funeral last month.Rodriguez was convicted on "unfounded and inaccurate" testimony, a prosecutor said.