If the chair doesn’t get them, the polygraph will

Monday, April 30, 2007 | 7:35 a.m.

It's a skeletal metal chair shoved up against a low white wall in a long unlit hallway in a crumbling government building.

It's where sex offenders go to give up.

Where sex offenders on parole and probation sit and fill out lengthy questionnaires about their personal lives : where they've been, who they're with, how they're spending the weekend.

Where they sit and wait for a polygraph test to prove it.

Lie detector tests are so daunting that about 80 percent of sex offenders monitored by Nevada Department of Public Safety Parole and Probation Division admit to breaking rules even before the test begins.

Pausing to think, parole officer Debbie Lupe says, gently, that the polygraph test "encourages honesty."

It's when they're sitting in the chair, alone and answering the questionnaires, that truth starts slipping to the surface.

"That's typically when they start admitting," Lupe said. "They don't want to fail the polygraph, so they just tell the truth."

Admissions often result in arrests.

Sex offenders are required to abide by 18 basic rules that may include keeping out of movie theaters and away from parks or staying sober and obeying a curfew.

The burden of proof is lower for sex offenders, so admitting to breaking the rules can quickly land an offender in cuffs, en route to the Clark County Detention Center.

On Thursday, Lupe waits to test a man who sexually assaulted his teenage step daughter, slinking into her bedroom while she slept.

It's been about five years since the offense. So far, the man has been well - behaved. This makes Lupe nervous.

"It's always the ones you never expect," she says.

Half of the last 10 polygraphs performed by the Parole and Probation Division have resulted in an arrest. A sixth offender was given extra restrictions.

Some offenders admit to making mistakes, then go on to "miserably fail the polygraph test," Sgt. Chris Dreyer said.

This is a sign the offender is minimizing bad behavior or hiding bad habits. Parole officers will read him the result - "deceptive" - and wait for an explanation, which usually turns into a further admission, Lupe said.

"On the surface, they want to make it seem like they're behaving," she said.

Lupe is monitoring one man who has figured out how to throw the machine, using some techniques to skew the polygraph reading. His tests have come up "inconclusive." She'll keep testing until she gets something.

"There's always something," she said.

Almost everyone reads up on how to fake out the machine, Dreyer said.

The bottom line: "It doesn't work."

Parole and Probation monitors approximately 730 sex offenders in Southern Nevada. Every month, 30 are tapped to take a lie detector test.

The polygraph process can take three hours or more, most of the time spent in interviews with the sex offender.

The actual test takes no more than 20 minutes. It's typically seven questions, asked a few different ways, just to be sure.

The parolee Lupe tested Thursday came up clean.

This is the way every test should work, Dreyer said.

"If you haven't done anything wrong, you have nothing to worry about."