Are innocent people behind bars?

New testing is revealing new light on dozens of cases where the Houston Police Department crime lab made errors in criminal cases.

For the last year and a half, a small team led by a local attorney has spent countless hours poring through old evidence in dozens and dozens of serious crimes. The cases were closed and the suspects convicted, but because of doubts about the HPD crime lab's work for the better part of two decades, some of the men and women put behind bars years ago are getting a second chance to prove their innocence.

On the 20th floor of the criminal courthouse in a small office, you find name after name lining the walls. Next to the names are crimes.

"All of the cases are serious cases. Murders, sexual assaults, that sort of thing," said attorney Bob Wicoff.

To Wicoff, every one of these names has meaning and every one of them is a case where the HPD crime lab made a mistake.

"We have cases where it looks like crime lab employees actually changed the results of their testing to fit who they thought was the guy," said Wicoff.

All 160 of the cases were referred to Wicoff and another lawyer by Michael Bromwich, whose investigation into the crime lab's faulty work found so many problems which all involve serology.

"Serology is basically body fluids. Blood, semen, saliva," said Wicoff.

It was the work done in this office that freed Gary Richard just last week.

"Gary Richard is very satisfying," said Wicoff.

Richard went to prison for a crime Wicoff found he could not have committed based on new scientific testing. He spent 22 years behind bars.

"It's a blessing," said Richard.

Wicoff said Richard is the exception and that most of these names and cases are ultimately unaffected by whatever errors the crime lab made. However, there are still more where Wicoff suspects innocence but evidence no longer exists.

"There must be incredible frustration and heartbreak for guys who are sitting in prison, who i have sat with in prison, who have a really strong claim but we can't prove it," said Wicoff.

Yet, still he works, trying to find the truth about the names that line the walls.

Wicoff said he hopes to finish the preliminary work on all 160 cases by the end of the year. Then he expects to post his findings for all of the cases online. There could be as many as a half dozen convicts who see new trials.

Harris County District Attorney Pat Lykos has taken steps to make sure evidence is handled properly when it gets to the HPD crime lab. In March, Lykos started requiring DNA tests in all cases where it's available. The change was made after an innocent man's DNA wasn't screened before he spent more than five years in prison.