Man Admits Kidnapping, Officers Say : Crime: The suspect also allegedly stole a vehicle, but denies seeing the owner, a missing Westlake woman.

A 19-year-old Thousand Oaks kidnaping suspect arrested in Nevada this week admitted that he took a missing nurse’s truck last week, abducted his ex-girlfriend and drove her to Reno in it, Ventura County detectives said Tuesday.

But Mark Scott Thornton denied he ever saw the nurse on Sept. 14, the day she disappeared, said Sheriff’s Lt. Lary Reynolds.

Thornton, who is known by his stepfather’s last name--Sarrazin--is scheduled to face an extradition hearing today in Reno, authorities said. He is being held without bail at Washoe County Detention Center in Reno.

Reynolds said that Thornton told detectives he found 34-year-old Kellie O’Sullivan’s black 1991 Ford Explorer empty outside a Thousand Oaks pet shop and took it because the keys were inside.

Thornton also admitted abducting 16-year-old Stephanie Campbell later that night and driving her to Reno in the truck, Reynolds said. Stephanie walked away from him at the Circus Circus Hotel & Casino there early Monday while he was playing a video game, and police arrested him moments later as he was using a house phone to have her paged.

But the teen-ager denied he had any role in the disappearance of O’Sullivan, a Westlake nurse who was last seen in the car about nine hours before the alleged abduction, Reynolds said.

The arrest shocked Thornton’s parents, who said Tuesday they could never imagine their polite, inarticulate, learning-disabled son hurting anyone, much less kidnaping his ex-girlfriend or taking a truck by force.

“It’s just an unbelievable thing,” Markita Sarrazin said Tuesday afternoon. “He wouldn’t hurt a flea. He’s so quiet and so timid. He’s very, very withdrawn. He’s not a troublemaker by any means. He’s more of a follower.”

Meanwhile, volunteers searched the rugged hills of Thousand Oaks by horseback, helicopter and four-wheel-drive vehicles for any sign of O’Sullivan.

By nightfall, the search had swelled to include about 80 to 100 volunteers and sheriff’s reservists, plus specially trained search-and-rescue dogs.

O’Sullivan, still dressed in her nurse’s uniform from a morning shift at a Canoga Park clinic, was last seen in Thousand Oaks about 2 p.m. Sept. 14, police said.

The pet shop owner said Tuesday he remembered someone who resembled her coming in to buy bird seed for a baby African gray parrot, but neither he nor owners of neighboring stores remembered seeing her black Ford Explorer. The O’Sullivan family says she owns such a parrot.

Sheriff’s helicopters scoured Wildwood Park and Hill Canyon, where criminals have dumped stolen cars in the past. “We’re just flying and looking for something white,” said sheriff’s helicopter pilot Chris Spangenberg.

“There are people who have gotten involved with this (search) who don’t even know Kellie,” said her ex-husband, Cliff O’Sullivan. “What we really need now is able-bodied people to help search.”

O’Sullivan’s family said the FBI has joined the investigation because the case involved interstate flight, although FBI agents refused Tuesday to confirm or deny whether they are involved.

As the search went on, Thornton’s parents groped for understanding what had happened to their son.

By their accounts, he grew up a happy kid who loved playing with toy cars, but then began to have brushes with the law that included a burglary arrest last November.

“He was never, ever allowed to play with (guns) as a child,” Markita Sarrazin said. “He raced Matchbox cars. It’s been something since he was very small. It was never a gun he played with, it was a car.”

She added: “I can’t see him holding a gun to someone and telling them, ‘Get in the car.’ If he wanted anything, it was the car because it had keys in it. I can’t see him hurting anybody.”

But Lt. Reynolds said that the .38-caliber snub-nose revolver that Thornton pulled out just before police arrested him--the one he allegedly used to force Stephanie into the car a week earlier--was reported stolen in a Thousand Oaks house burglary in July.

Thornton has always been smart, but he has trouble articulating his thoughts, his mother said.

“If you look at his test scores, he’s very intelligent,” she said. “He’s just not able to communicate.”

This learning disability kept him in special-education classes throughout Hoover High School in Glendale, then at schools in Thousand Oaks when his family moved there about 18 months ago, she said.

From age 12, he and his stepfather loved racing radio-controlled cars on special tracks, competing at places like Bakersfield and Del Mar.

Thornton harbored ambitions of becoming a professional race car driver and even fantasized about going to a sports driving school, his mother said.

He introduced her to Stephanie earlier this summer, she said, but she thought little of it, figuring boys have a lot of girlfriends.

In recent months, however, Thornton began to treat his parents disrespectfully, his mother said. He told “little white lies,” ignored pleas to look for summer jobs, cannibalized his stepfather’s remote-controlled car for parts and siphoned gas out of the man’s car, his mother said.

Thornton wanted to move out and began spending nights at friends’ houses, she said.

While driving the Datsun B-210 given to him by his stepfather, Pierre Sarrazin, Thornton piled up five traffic tickets, often for speeding to friends’ houses in Los Angeles, Pierre Sarrazin said.

By June, 1992, a month before his 18th birthday, Markita Sarrazin said she was ready to grant Thornton’s wish and let him go. He was not being a good example for his 12-year-old sister, and it was time for him to learn some responsibility.

“I told him to go,” she said. “I put his things outside, I put some money in his jacket pocket, and he came back with the sheriffs. And the sheriffs said he can’t go because he’s not 18.”

He moved back in, but continued spending nights away from home.

Although court records show that Thornton was convicted of burglary as a juvenile and as an adult, his mother continued to insist Tuesday that he was a good child.

The adult burglary arrest came last November. According to Ventura County probation records, three witnesses told police that someone driving a Datsun pickup truck had stolen three bikes out of a carport on the street.

Police traced the pickup to Thornton and found the stolen property in his vehicle, according to the probation report. A juvenile later arrested in the case told authorities that Thornton had also been involved in three auto burglaries that same day.

Thornton told a probation officer that he had been living with his mother and stepfather in Thousand Oaks, but left the day of the crimes because he could no longer get along with his parents. He said he met some friends and they planned the break-ins.

He served 60 days at the Ventura County Jail, which released him Feb. 10, 1993, records show.

Thornton stayed at home off and on, but finally moved out in May, Markita Sarrazin said. The last time she saw him before his arrest was about four weeks ago.

“You spend so much energy on children, and you try . . . “ she said, holding back tears. “They get out on their own, and they kind of change, I guess.”

She worries about how her son is dealing with police interrogation.

“For the police to talk to him has got to be a very confusing thing to him,” she said. “He’s not reluctant; he just doesn’t know how to talk. That’s why he had a problem with us. He doesn’t know how. “

Pierre Sarrazin said: “I’m pleased he’s caught, in that he won’t cause any more damage than he did. Now, they need to help him.”

His mother added: “Maybe we should have gotten some counseling for him. It’s hard, because he’s such a good boy.”

Times staff writer Dwayne Bray and Times correspondents Brenda Day, Tommy Li and Jerry Mennenga contributed to this story.