It was a novel case: a Texas man accused of knowingly infecting six former girlfriends with the HIV virus.
And prosecutors hit on a novel solution, charging Philippe Padieu, 54, with aggravated assault with a deadly weapon. The prosecution maintained that Padieu knew he had the HIV virus and did nothing to protect his partners.
external">May 2009 court case Padieu finally came face-to-face with his accusers.
The six victims were instrumental in helping to build the case against him.
Padieu's attorney argued that his client was in denial after receiving an HIV-positive diagnosis in 2005 and was unaware of how much harm he could cause others. The defense also said Padieu's ex-girlfriends shared the blame.
For the full story watch "20/20" tonight at 10 p.m. ET. For Part 1 click HERE.
"You need to be responsible for your own health," the attorney, George Giles, told the jury.
While the women disagree with the assertion that they were also responsible, such potential gray areas have made criminal cases involving HIV very difficult to prove.
Cases involving HIV have been both difficult to prosecute and controversial. Thirty-two states have made it a crime to knowingly infect or risk infecting others. Texas has no such law. In Padieu's case, his own DNA may have been the star witness against him.
Dr. Michael Metzker, a professor of genetics at Baylor College of Medicine in Houston, was asked by the prosecution to conduct a study comparing blood samples from Padieu and the six women.
DNA sequencing can show how two HIV strains are related and which one is the source, Metzker said.
"One sample, sample one, was the source of most if not all of the other samples' infection," Metzker testified in court.
Sample one was taken from Padieu.
The jury found Padieu guilty, and he was sentenced to 45 years in prison. But Padieu says he did not set out to intentionally harm his accusers.
"I believed I had a false positive," Padieu told "20/20" from his cell at the Collin County Correctional Facility. "I think we tend to believe everything is going to be OK, and I believed that I was negative."
He rejected Metzker's testimony which pointed to him as the source of the infection.
"We are all responsible, this was consensual sex. We all agreed to have sex," said Padieu. "Are they not a willing participant? I didn't create the HIV virus. One of these women knowingly and intentionally infected me."
Find out what else Padieu had to say about the case tonight on "20/20" at 10 p.m. ET
But "20/20" obtained test results which show Padieu may have been infected with the HIV virus for more than a decade before the Texas case.
A woman ABC News is calling "Lisa" to protect her identity dated Padieu in 1997, when he lived in Detroit. They were intimate. Years later, Lisa got married and applied for life insurance. Not only was she denied the insurance, but she received the bombshell news that she had tested HIV-positive.
"I just fell to the floor," Lisa told 20/20. "I wanted to commit suicide. I felt like my life was over."
After searching for Padieu's name on the Internet, Lisa came across articles about a Texas man arrested for infecting women with HIV. It was Padieu, the man she had been intimate with years before.