Thornton Jury Hears Closing Argument : Courts: Prosecutors urge panel to convict defendant of first-degree murder and special circumstance. Deliberations begin Monday.


After seven weeks of testimony, the jury in the Mark Scott Thornton trial heard its final argument Friday and next week will begin deliberating the fate of the man charged with murdering Westlake nurse Kellie O’Sullivan.

Ventura County Superior Court Judge Charles R. McGrath ordered deliberations to start Monday morning.

In a two-hour session, the jurors listened as prosecutors made one last attempt to persuade them to convict the 20-year-old defendant of first-degree murder and a special circumstance that could send him to the gas chamber.


Deputy Dist. Atty. Peter D. Kossoris appealed to the jurors’ sense of indignation, arguing that Thornton went to a tattoo parlor shortly after firing three bullets into the victim in the Santa Monica Mountains on Sept. 14, 1993.

“Can you imagine a guy kidnaping a woman, taking her up there, shooting her twice in the back and once in the chest and going to get a tattoo with his girlfriend’s name on it?” Kossoris asked.

O’Sullivan, he said, “was executed in the most cold-hearted, cowardly way. She’s left there . . . and her body isn’t discovered for 12 days.”

Kossoris’ rebuttal argument came one day after defense attorneys admitted their client killed the 33-year-old nurse. Thornton’s lawyers argued that the slaying was unintentional and perhaps caused by O’Sullivan, who they said might have lunged at the defendant. They characterized Thornton as immature, impulsive and a slow learner.

Kossoris called the defense theory of the murder “absurd.”

Around the time of the slaying, Thornton was a “one-man crime wave,” Kossoris argued, noting that the defendant is also charged with forging checks, stealing the murder weapon and later using O’Sullivan’s stolen truck to kidnap his former girlfriend and shoot at her mother.

The defense tried to pick apart the prosecution’s case in part by saying no credible witnesses ever saw Thornton harm O’Sullivan. But Kossoris noted wryly, “Most murders are not committed before any audiences.”


He said the only one who knows precisely what happened to O’Sullivan is Thornton, who had denied strongly to authorities that he killed the nurse.

He said Thornton should be convicted of the special circumstance because he murdered O’Sullivan while committing a robbery. Thornton, Kossoris argued, kidnaped O’Sullivan around 2 in the afternoon to steal her Ford Explorer truck. He then killed the woman so she would not report the crime because he needed time later that night to kidnap his former girlfriend when she got off work, Kossoris said.

“In this case, escape and avoiding detection is very important,” Kossoris said. “Remember, this guy has a warrant out for him.

“It doesn’t take a Harvard Phi Beta Kappa (to realize) that if he just left her somewhere, she’s going to go to the road and flag someone down.”

If the jury finds the defendant guilty of the special circumstance, it would then hear a second trial to decide his penalty: either death in the gas chamber or life in prison without parole.

During his argument, Kossoris often pointed at Thornton and called him a liar.

“He can swear on the Bible something he knows is a total falsehood,” the prosecutor said.

He also criticized the defense for attacking prosecution witnesses, including 17-year-old Stephanie Campbell, Thornton’s ex-girlfriend. After the nurse’s murder, Thornton allegedly kidnaped Campbell and drove around Northern California with her for five days before going to Reno, where he was arrested. The defense contended Campbell was with him willingly and lied in her testimony when she said he threatened to kill her if she tried to leave him.


“Stephanie was as credible a witness as you will ever see,” Kossoris said.

He added that Campbell is “a nice, clean-cut, honest girl who made only one big mistake in her life--and that was to get involved with this coldblooded killer you see at the defense table.”