Eaton, Ohio is a quiet rural town where neighbors know each other, look after each other, and where lies eventually catch up with the liars.

Tim Johnson grew up in Eaton. Adopted around age 10, Tim had also had an older foster sister, Pamela Henry. After Tim's father passed away he began living with and caring for his wheelchair-bound mother, Nancy.

So when Tim Johnson went missing, people paid attention.

"Initially, the call came into our agency here, the sheriff's office from a family member of Tim's concerned for his whereabouts," said Preble County Sheriff's Detective Dean Miller.

Reportedly, his sister Pamela was the last person to see Tim. But a different family member alerted the authorities that he had disappeared.

Tim's foster sister Pamela Henry was living at the house with their mother as well. Pamela's boyfriend, Adam Scott, 19 years her junior, would stay over sometimes too.

A few weeks after Tim went missing, family members noticed concerning signs and began to become suspicious, according to Miller. Personal items of Tim's, like tools and a computer, came up missing.

"Tim owned two cars. The family found those had been driven by Pamela and Adam Scott, which would not be normal," said Miller.

Pamela and Adam seemed to have logical explanations for everything, like how Adam was buying one of the vehicles from Tim. But not everyone was buying the logic.

"At that point we said OK, we see your suspicion here," said Miller.

Detectives went to the house Tim shared with his mom and Pamela and found personal items that raised big questions. In the house Tim's wallet, checkbook and calendar were found.

"We found a calendar that recorded different things that he had done, and then you come up to that particular date and nothing after that. Not a thing, so that told me that something happened abruptly," said Lindloff.

Needing to know more, investigators contacted Pamela to see what she knew about Tim's disappearance. Pamela seemed more than cooperative.

"Pam denied knowing anything about his whereabouts, and even provided us with an explanation of an argument that he and she had at the home, and that Tim left in a dark-colored vehicle with someone else that picked him up," said Miller.

Detectives asked Pamela Henry and Adam Scott to come down to the station to return Tim's vehicles and to talk more about Tim's possible whereabouts.

"Both Pamela Henry and Adam Scott came to our office of their own free will," said Lindloff. "Pamela was very cooperative, didn't seem to be real nervous about anything. Adam Scott, he was really kind of a jolly, happy guy, he was very pleasant to talk to. He was very polite."

Then detectives asked Pamela the question that would change the course of their investigation.

"We offered her this test, and if you're good, you're good," said Miller.

Pamela Henry agreed to take the test -- the Computer Voice Stress Analyzer (CVSA).

"It's basically sitting down, having a casual conversation with somebody and we put a microphone on and we record their yes and no answers," said Master CVSA Examiner-Instructor William Endler.

Unlike the polygraph, some experts say the CVSA is more than 95 percent accurate, but is only used as a tool in an investigation.

Investigator Lindloff, who is also a certified voice stress analyst, administered the test. Pamela went first.

"She sits down and goes like this [arms crossed], and right away that's a defensive posture that she's taking, it's almost like 'Bring it on,'" said Lindloff.

Investigator Lindloff would ask both relevant and irrelevant questions. She denied withholding any information about Tim's disappearance.

Then it was Adam's turn.

"He showed all kinds of indicators: Rubbing his face, he was rubbing his eyes, and he was extremely nervous," said Lindloff. Adam also denied withholding information about Tim's disappearance.

The tests concluded and soon the results would be in.

The CVSA is an investigative tool like a polygraph, but according to some experts, it's more reliable.

Computer voice stress analysis expert Bill Endler has been teaching the process for 16 years to law enforcement agencies in the United States and around the world.

Endler finds the CVSA more reliable than the polygraph because the polygraph can be manipulated, and the CVSA cannot.

"With the polygraph there are several countermeasures that a subject could do to basically manipulate the chart," said Endler. "They can control their breathing. Whereas with the CVSA there's really nothing they can do to manipulate it."

Researchers have learned that when the brain perceives punishment, physiological changes occur.

"The muscles your voice box tighten up so when you speak the air passes over, it still vibrates, but it doesn't vibrate at the same rate that it does when we're relaxed," said Endler.

Adam's and Pamela's CVSA test results were ready. It was the moment of truth.

"After both Adam Scott and Pamela Henry completed their CVSA tests, David Lindloff told us there's deception," said Miller.

"I think I asked Pam three relevant questions. The relevant questions showed deception on them," said Lindloff.

"Just in a matter of seconds we went from a missing-persons investigation to a homicide investigation," said Endler.

Then the two were shown the deception in their tests.

"Both of them admitted when confronted with the results of the test, 'Yes, we killed Timothy Johnson,'" said Lindloff.

After a few differing versions, detectives finally learned exactly how Pamela and Adam maliciously murdered Pam's brother Timothy.

"Adam Scott overpowered him, put him in a chokehold," said Miller. "Pamela began to wrap his face and his head with plastic Saran Wrap. They were struggling, so Adam finished wrapping that around Tim's face."

Investigators then learned what Pamela and Adam did to Tim's body after they killed him.

"They attempted to burn the body, then they ended up concealing the body in a barrel, filled that barrel with concrete on top of his body. They were going to put this barrel in a truck and haul it down to the river and throw it off the bridge," said Miller. "As it turns out the barrel became too heavy to move."

When detectives went to Tim's house, in the barn they found the barrel filled with cement -- and Timothy. It weighed over 700 pounds.

"We had to remove Timothy's body with air chisels," said Miller.

Detectives soon learned the alleged motive was greed and jealousy. Tim was set to inherit everything after their ailing mom passed away.

"Had we not done the voice stress test, I think they would have gotten away with murder," said Lindloff.

Detectives credit the CVSA with getting their confessions.

Pamela Henry and Adam Scott were both convicted of murder and abuse of a corpse. Pamela was sentenced to 25 years to life and Adam Scott was sentenced to 20 years to life.