Missing Nurse Found in Hills Was Killed by Gunfire : Autopsy: Kellie O’Sullivan’s body was discovered in the Santa Monica Mountains. Suspect in her disappearance will be arraigned today on undisclosed charges.

A Westlake nurse whose decomposed body was found Sunday in a heavily wooded gully in the Santa Monica Mountains died of multiple gunshot wounds, the Los Angeles County coroner’s office said Monday.

A dental consultant confirmed that the body was that of 34-year-old Kellie O’Sullivan by comparing her dental X-rays with X-rays of the body, which was found Sunday beneath an oak tree in the 33500 block of Mulholland Highway in western Los Angeles County, said Scott Carrier, a coroner’s spokesman.

Carrier declined to say more about the slaying, but said the autopsy performed Monday found no evidence of sexual injury on O’Sullivan’s body.

“The police have requested we not release information as to what part of the body (was shot) or any great details,” he said.

Meanwhile, 19-year-old Mark Scott Thornton, who Ventura County detectives have said is the prime suspect in O’Sullivan’s disappearance, is scheduled to be arraigned this afternoon in Ventura County Municipal Court.

Deputy Dist. Atty. Peter D. Kossoris, Ventura County’s senior homicide prosecutor, declined to say what charges he expects to file against Thornton.

Thornton appeared briefly in Municipal Court Monday for a hearing on charges that he violated probation stemming from a burglary conviction, but that hearing was postponed. He also made an appearance in Ventura County Juvenile Court, which is closed to the public.

Thornton was booked into Ventura County Jail Sunday on suspicion of kidnaping and assault with a deadly weapon for allegedly abducting his 16-year-old ex-girlfriend, Stephanie Campbell, and firing a shot at the girl’s mother before he drove away.

The abduction occurred at about 11 p.m. Sept. 14, about nine hours after O’Sullivan was last seen leaving a friend’s office in Westlake while running errands.

Police in Reno, Nev., arrested Thornton five days later.

Just before midnight Sept. 19 at the Circus Circus Hotel and Casino, Stephanie slipped away from him and summoned help while he was engrossed in a video game. When Reno officers confronted him, he was using a house phone at the casino, trying to have Stephanie paged, police said.

Thornton pulled out a .38-caliber snub-nosed revolver and tried to get away, but police drew their guns and wrestled him to the ground, officials there said.

Although Reno authorities booked him on a fugitive warrant under the name Thornton, Ventura County deputies booked him last weekend under his stepfather’s last name--Sarrazin--which authorities and relatives said the suspect has been using for some time.

Reno police found O’Sullivan’s black 1991 Ford Explorer parked a few blocks from the casino. Court records show that Ventura County detectives who searched the truck found a variety of clothing, camping gear, toiletries and hand tools.

The search also turned up an insurance card in O’Sullivan’s name, along with a black purse containing 41 .38-caliber bullets--the same size ammunition found in the gun Thornton had in hand before he was arrested, records show.

Detectives said Thornton told them he found the Ford empty with the keys inside and admitted using it to abduct Stephanie. But they said Thornton denied ever seeing O’Sullivan and that the girl also said she never saw O’Sullivan.

O’Sullivan’s disappearance sparked a massive search, as up to 275 civilian volunteers and 35 Ventura County Sheriff’s Department personnel spread out over 170 square miles of rugged, brush-choked countryside around Thousand Oaks.

When two civilian searchers discovered the body early Sunday, Los Angeles County homicide investigators took over the crime scene, collecting evidence and photographing the area.

However, late Monday, after conferring with Ventura County investigators, they decided to hand over the homicide investigation to Ventura County for further work, said Deputy Gabe Ramirez of the Los Angeles County Sheriff’s Information Bureau.

Lt. Craig Husband of Ventura County’s major crimes division said Monday: “It appears we’ll be handling it since the majority of the incident involving the abduction of Sarrazin’s girlfriend occurred in Ventura County.”

Times staff writer Dwayne Bray contributed to this article.