Four years ago, a Houston teenager named Josiah Sutton was convicted of rape and sentenced to 25 years in prison.
He was convicted primarily on the basis of DNA tests performed by the Houston police department's crime lab.
But is he a rapist? The DNA said so, and that was enough for the jury. It probably would be enough proof for most of us, who have come to believe DNA is foolproof.
Correspondent Vicki Mabrey follows one case, first reported by KHOU-TV, a CBS affiliate in Houston, that is sure to turn your assumptions about DNA upside down.
In 1998, on an October night, a woman was abducted at gunpoint by two men from the parking lot of her apartment complex in Houston. She was driven in her car to an isolated spot and raped by both men.
Five days later, she passed a group of men on the street, and identified two of them to police as her attackers. Josiah Sutton, 16, and a friend were arrested.
"I never knew and I kept getting questions, 'What am I here for? What am I here for,'" says Sutton.
In jail, Sutton and his friend found out they were accused of kidnapping and rape. They said they were innocent, and Sutton's mother, Carol Batie, thought it was a case of mistaken identity that would be quickly cleared up.
"When I first got the police report, the description of the suspects did not fit Josiah's description at all," says Batie, Josiah's mother.
Police were looking for a 5-foot-7-inch man who weighed 135 pounds.
"Josiah's never been thin since birth, so at the time, I had proof and identification, his ID, that stated he was 6 feet tall, and 200 pounds," says Batie. "So, I said, 'OK, they should look at that and let him go.'"
But police thought they had their man and the evidence to prove it – semen taken from the crime scene that they could compare with Josiah Sutton's DNA.
"I knew that the DNA would be able to clear me," says Sutton, who voluntarily submitted a DNA sample. "I knew that DNA was something people had a lot of faith in, that I was told, you know, gave the truth."
Sutton's blood sample was taken to the Houston police department's crime lab, where analysts compared it to semen samples taken from the victim and from the backseat of the car where the rape occurred.
For two months, Sutton waited in jail. He says he was confident that the tests would free him. They cleared his friend, but his lawyer had different news for him.
"He said, 'I just got your tests back. They came up with a positive ID on you, as far as the testing.' And I told him, I said, 'No, that's impossible.' My exact words were 'There's no way on God's green earth.' And he said, 'Well, I'm sorry, man, but that's what they came up with.'"
The lab's report was definitive. It said that DNA consistent with Sutton "was detected on the vaginal swab taken from the victim and on semen 'Sample Number 1' found on the backseat of the car." It also said Sutton was a one-in-694,000 match.
It was a slam dunk for the prosecution. The jury took less than two hours to find Sutton guilty. He was sentenced to 25 years.
"I still don't believe it to this day," says Sutton. "It couldn't be right."
Like a lot of prisoners, Sutton continued to proclaim his innocence and he set out to prove it. He studied DNA in the prison library, and three years after his arrest, he handwrote a motion requesting a DNA retest. But he wasn't getting anywhere until something unexpected happened.
Two reporters at KHOU-TV in Houston received a tip from defense attorneys that there were problems in the police department's crime lab.
Anna Werner and David Raziq decided to investigate. They dug up transcripts and lab reports from several cases and sent them to a group of experts, including University of California criminology professor William Thompson, who has reviewed DNA evidence from labs all over the country.
How did the Houston police crime lab stack up?
"It's the worst I've seen," says Thompson. "This doesn't meet the standard of a good junior high school science project."
"I found consistent distortions of the statistical certainty of the DNA evidence. I found instances that looked like fudging of results, to fit the prosecution's theory of the case. And I found a lab that consistently failed to use appropriate scientific procedures."
KHOU broadcast their story about the crime lab last year, and Carol Batie, whose son had been in prison for four years by then, was lucky she caught the 10 o'clock news.
"I immediately jumped up and I started thanking God," says Batie, Josiah's mother. "I said, 'Here is our key, this is our answer.'"
Batie convinced KHOU to investigate her son's case. And Werner and Raziq sent his file to Thompson, who says the mistakes in the lab's original report practically jumped off the page.
"After reviewing the case for a couple of hours, I became convinced that Mr. Sutton was very likely to be innocent," says Thompson. "This appears to be a pretty clear example of misrepresentation." He then examined the crime lab's original DNA test strips from 1998 and saw that the analyst had reached conclusions that were just plain wrong.
Remember the lab report that said Sutton's DNA could be found in "Sample 1" on the backseat of the car where the rape took place?
"This sample here is the sample from the backseat, which according to the lab report matched Sutton, or which included his profile. Josiah Sutton's sample here, he has two markers on this system that are labeled 1 and 2," says Thompson. "The sample from the back seat has two markers that are labeled 2 and 3. It does not appear to have the 1 marker, which Sutton has. And that would indicate that the sample in the back seat could not have come from Mr. Sutton."
And with only a little more work, Thompson concluded that Sutton's DNA wasn't found in any of the samples.
"You have to think something's wrong, when a college professor can look at lab records for a couple of hours, and figure out that somebody who's been sent to prison for 25 years is likely to be innocent," adds Thompson.
His findings convinced police to have the DNA from Sutton's case retested at an independent lab. That test was conclusive: Sutton's DNA was not found in the sample. That convinced a judge who ordered him released on bail. Today, he is waiting to see if he will be pardoned.
60 Minutes II wanted to ask Houston police chief C.O. Bradford how his crime lab could have made such a terrible mistake. Bradford wouldn't talk; neither would the head of the crime lab. All cited an ongoing investigation.
As a result, 60 Minutes II asked forensic scientist Elizabeth Johnson, who monitored Sutton's retest for the defense, to explain how this could have happened.
"[Most people] think it's absolute and black and white and infallible," says Johnson. "But it is not. The testing has to be performed correctly in the first place and interpreted correctly in the second place."
Johnson, who used to be director of a different lab in Houston, showed 60 Minutes II how evidence can be tampered with or contaminated. She doesn't think that happened in Sutton's case.
Her theory is that it had more to do with a problem that's found in many cities when crime labs are located in police departments and analysts can feel pressured to be "cops in lab coats" - trying to make the science match the police department's case.
"Too much of the time the police or the detectives come in and they submit evidence and they stand around and visit for a while and start telling chemists their version of what happened in the crime," says Johnson. "That's a dangerous situation."
Thompson's theory is similar, and it's just as tough on the Houston police department's crime lab.
"I think that the Houston Police Lab has personnel that are not particularly competent, who are working under situations where they have incentives to distort their findings in favor of the police and prosecution," says Thompson. "So I think that we have a situation where they may be making up for their incompetence with bias."
Amid all the accusations about the crime lab, the Houston Police Department ordered an independent audit of the lab's technical operations. That investigation resulted in a scathing 50-page report that chronicled a litany of problems - everything from inadequately trained staff, to possible contamination of evidence, to unnecessarily using up all the evidence from a crime - making any future retesting impossible. The lab was shut down immediately.
Another investigation is now under way to determine if there was any intentional fraud committed by laboratory personnel.
But the story doesn't end there. Hundreds of other convictions in Houston are now being called into question. Harris County district attorney Chuck Rosenthal and assistant DA Marie Munier must review 10 years worth of cases their office has prosecuted using evidence from the lab.
"It seemed like someone from the Houston police department would have had enough inquisitiveness to have looked at that," says Rosenthal.
But why would the district attorney's office accept everything on blind faith – especially when the defense is bringing in expert witnesses to counter what they are saying?
"We're not equipped with enough scientific knowledge to question a lab like that," says Munier. "So we basically go on good faith. Unless there's something that slaps us in the face, which is what this has all done to say, 'Hey, look there is a problem here.'"
So far, Munier says they've reviewed hundreds of cases, and nearly 200 have been pulled for retesting – including the cases of 17 men awaiting execution on the busiest death row in the country.
How likely is it that some of these other defendants are not guilty, just as Josiah Sutton was innocent?
It's too soon to say, believes Munier. "There's probably more, but we don't know which ones they are yet."
Of the nearly 200 cases being retested, 15 have been completed. So far, in addition to Josiah Sutton, one other test has uncovered inconsistences and is still being reviewed.