CLEVELAND -- In the spring of 1999, Yvonne Layne, a young mother of 5, was found in a pool of her own blood.

Joe Wilkes was convicted of her murder and David Thorne was convicted of hiring him.

After investigating the case for seven years, Sue Gless, a postal clerk turned amateur investigator, said both men are innocent of the crime that landed them life in prison.

She said she is 100 percent convinced these men did not do it, reported NewsChannel5 chief investigator Duane Pohlman.

Layne lived with Linda McLaughlin's son, Erick Cameron, in McLaughlin's home for four years. McLaughlin and others said Layne had a dark side.

"She just played so dangerously," said McLaughlin.

Police said they knew Layne had been a prostitute and topless dancer and that she had many sex partners.

"I know she had some history," said former detective John Leech.

Detectives originally identified Cameron as the main suspect in the murder, but there was a problem.

"He was in jail at the time," said Leech.

So, how did this trail lead to Thorne? Police had a theory and a motive. Thorne was the father of one of Layne's children and a court had just ordered him to pay child support weeks before Layne was killed.

But the custody arrangement between Thorne and Layne was described in testimony as "agreeable" and "congenial."

"She and I had a decent relationship," says Thorne.

Detectives soon targeted another young man, Joe Wilkes.

Pohlman: "You were going to have sex with Yvonne?"

Wilkes: "Yes."

On the night Layne was killed, Wilkes admits he went to Yvonne's home.

"She told me she was supposed to have some company and for me to come back later on," said Wilkes.

Pohlman: "Did she tell you who the company was?"

Wilkes: "No."

Wilkes said he went back an hour later, entering a bloody mess.

"I found her laying on the floor, dead, blood all over the place. I stepped over the body and went to see if the kids were all right, and the door was locked so I knew they were in there, and I left," Wilkes said.

Scared and confused, Wilkes said Leech forced him to confess.

"They told me the general story about how to put David in it," said Wilkes.

Leech said that never happened.

Wilkes is now serving life in prison. Thorne is serving life, too, convicted in a murder-for-hire plot.

"I don't care what they say, you're guilty until you prove yourself innocent," said Thorne.

A criminal justice textbook written by forensics expert Brent Turvey included a chapter on how not to investigate a crime scene. That chapter talks specifically about the investigation of Layne's murder.

"It's like they didn't even care. The best word to describe it is inadequate, severely inadequate, and to the point of belligerently inadequate," said Turvey.

A detective taking photos of the crime scene included his own footprint and police covered the body with a blanket taken from Yvonne's bedroom, creating possible contamination.

Even the police chief brought an outsider to the murder scene.

"She is not a sworn officer so she probably ought not have been there," said Chief Dordea. "I would say I could have exercised better judgment."

The murder weapon was a problem, too. Detectives said the knife that killed Layne matched the one missing from her kitchen. It had a fingerprint that has yet to be identified.

But weeks later, the same detectives announced a knife, purchased by Wilkes, was the real murder weapon.

"We were able to recover the receipt from K-Mart where Wilkes had bought it, and you know that ties Wilkes to that knife," said Leech.

But the knife had no prints and what experts described as protein.

Wilkes said police brought him that knife.

On the stand, Wilkes said the police were the ones that told him how the murder was committed.

Wilkes confessed to killing Layne on the couch, reaching around her and cutting her throat.

But Turvey said the murder could not have happened way.

"It is not possible she received any of the injuries she received on the couch," said Turvey.

He said blood patterns tell the real story, that the killer struck while the victim was standing by the sliding glass doors.

"She begins to spurt blood pumping blood violently out of her neck. There are drag marks and smear marks in the blood. She's being assisted from the sliding glass door to the area between the couch," said Turvey.

That means the killer would have been covered in blood. But that wasn't the case with Wilkes.

Pohlman: "Where was the blood on your clothes that you were worried about?"

Wilkes: "On my shoe."

An expert said the system did indeed convict the wrong men.

"I can't think of a rational explanation for why they shouldn't get a new trial," said Turvey.