HOUSTON -- Note: The following story is a verbatim transcript of an Investigators story that aired on Tuesday, Aug. 12, 2008, on KPRC Local 2 at 10 p.m.

Tonight, Local 2 Investigates digs into the case of an inmate from Houston who has been on death row for more than 30 years. So why hasn't Raymond Riles been executed?

When you read and hear his first TV interview in more than 20 years, you may understand why.

His case has sparked a debate of what to do with inmates spending decades waiting for an execution. Local 2 investigative reporter Amy Davis uncovers why Riles' case could change the future of Texas' death row.

"They told me they were going to kill me unless I stopped preaching my mystic gospel," Riles told us during an interview from death row at the Polunsky Unit in Livingston. "God is the greatest and I didn't come to die on death row."

As Riles speaks, you're almost able to read his mind -- by not understanding it.

"They're trying to silence me because I know about the satanic secret societies of the TDC shadow government e-system," said Riles.

His mind appears mixed-up, full of delusions and paranoia. This is the latest chapter of Riles' story -- 33 years of crime and punishment.

Riles committed his crime back in 1974. He was convicted of killing Houston used-car salesman John Henry during a 1974 robbery. A Harris County jury sentenced Riles to death.

But 33 years later, Riles still waits on death row with no execution date and no plans for one.

"It's because he's incompetent to be executed," explained Roe Wilson, an assistant district attorney for Harris County.

Wilson handles death row appeals and says Riles case is that simple. Mental health experts have ruled Riles doesn't understand why his execution is imminent, or understand exactly why he's being executed. That makes him mentally incompetent, according to the U.S. Supreme Court.

"If you don't meet the standard, then you cannot be legally executed," said Wilson.

During our interview, Riles told us he believes God committed his crime, thinks he was chosen to release men from death row, and believes a lethal injection would not kill him.

Riles also blamed God for his prison suicide attempt in 1985. Riles set himself on fire in his cell.

"God did that," said Riles. "God consumed me in fire."

In 1986, Riles was inches from the death chamber in Huntsville and just minutes from execution. That's when a federal court issued a last-minute stay. It was the fourth time the state scheduled Riles' execution. A new date hasn't been scheduled for the past 22 years.

"As long as he's living, I'm still living," said Helen Riles, Raymond Riles' sister. "We're still living."

Helen Riles spoke to us from her Houston home. She's calls her brother's three decades on death row "bittersweet."

While Raymond Riles hasn't been executed, Helen Riles is fighting to get her brother off of death row and into a mental health facility instead.

"I don't think he could ever come all the way back," said Helen Riles. "I really don't. But he would able to feel more comfortable and get more rehabilitation."

And that's the debate. If an inmate can't be executed, should he or she remain on death row?

A new call is coming from a nationwide association of attorneys, death penalty opponents, and a U.S. group of mental health experts to change the way mentally ill inmates are treated on death row.

They all say a life sentence is more appropriate.

"It makes no sense for the state to keep someone on death row under severe conditions, when he's been recognized as severely ill," said Kristin Houle', with the Texas Coalition to Abolish the Death Penalty in Austin.

On death row, all inmates spend 23 hours a day in their cell.

Houle' calls that cruel and unusual punishment for the mentally ill, claiming it gives inmates little access to psychiatric care.

The state disagrees.

"That really is not a factor in this case," said Wilson. "What the factor is, is that (Riles) was competent when he was tried and given a legal sentence. His confinement is still legal and he simply has a condition right now that makes him not eligible for execution. But that could change."

That's right. Wilson says Riles is still periodically tested by doctors. His mental state and his future could always change.

Right now, Texas law doesn't allow a death sentence to be replaced by a life sentence.

Wilson argues Riles' punishment stands, no matter what his mental state is now. Many call that justice for the victims.

So, at age 58, Raymond Riles remains on death row -- 33 years and counting. His family and activists say they'll continue to work to change the law that keeps him there.

"I'm not just going to let him sit there and not fight for him," Helen Riles said.

Courts and doctors have ruled five other death row inmates from Harris County are also mentally incompetent to be executed. Any change in Riles' case or state law could have a direct effect on many Texas inmates.

However, those inmates are all tested periodically. If they are ruled competent at any time, an execution date can be scheduled.

Update On Wednesday, Aug. 13

Since our story aired, we were contacted by murder victim John Henry's son. Due to the more than 30 years since the crime was committed, Local 2 Investigates was unable to locate any family member of Henry.

His son's e-mail is below.

"As the only child of John Henry, I have grown accustomed to Houston news channels running Raymond Riles' story at least once every decade since his crime. I grow more disgusted with our penal and judicial system every time his story airs. In a cowardly action, Riles shot my father in the back of the head and left him to die. This never would have been possible, except that our court system paroled him early from a prior conviction. Riles is nothing more than a career criminal and yet HIS story is the one that news agencies deem worthy of reporting.

"Your stories only breed sympathy for people who have participated in horrendous crimes. Whether Riles is mentally insane or not, he deserves to (and should) die for his crimes. Instead of Riles' mental state, why don't you report on the irony of Riles' story. The fact that Riles murdered my father, and my tax dollars are keeping him alive is nothing short of ironic.

"Helen Riles made the comment, 'I don't think he could ever come all the way back, I really don't. But he would able to feel more comfortable and get more rehabilitation.' Please let Mrs. Riles know that there is nothing that will ever bring my father back, and since Texas will not execute her brother, his 'discomfort' on death row is my only peace."

By Jason Johnston