Thornton Lawyers Seek Reduction to Life in Prison : Courts: Attorneys cite jury bias in motion to have death-penalty recommendation overturned.

Alleging that Thousand Oaks killer Mark Scott Thornton did not get a fair trial from the jury that recommended he be put to death, defense lawyers now want the judge in the case to reduce the verdict to life in prison without parole.

In March, a Ventura County jury recommended that Thornton be put to death for the 1993 carjack slaying of Westlake nurse Kellie O’Sullivan, who was driven to a desolate area of the Santa Monica Mountains and shot three times.

Trying to persuade Superior Court Judge Charles R. McGrath to reduce the recommended sentence, Thornton’s attorneys accused jurors of allowing their emotions to interfere with deliberations.

“It would appear that the jury . . . was unable to remain objective during the penalty phase because of the obvious anguish of Kellie O’Sullivan’s relatives,” says the defense motion, which the judge is expected to review prior to Thornton’s scheduled May 15 sentencing. The motion also cited “the jury’s anger toward the defendant for the harm he caused.”

The defense also argued that state law requires McGrath to reconsider the verdict and that the death penalty is not warranted because Thornton was only 19 at the time of the crime, and because of other mitigating factors.

Prosecutors scoffed at the defense motion, saying Thornton’s lawyers are trying to reargue the case after the fact.

Deputy Dist. Atty. Peter D. Kossoris, who prosecuted Thornton, acknowledged that the jury related well with the victim, the mother of a 5-year-old son at the time of her death.

“It sure is appalling that the jury had some sympathy with the relatives of an innocent person who was kidnaped and left laying in the mountains to die rather than with a cheap, lying crook,” Kossoris said sarcastically.

The motion was filed by Deputy Public Defenders Howard J. Asher and Susan R. Olson, neither of whom could be reached for comment Monday afternoon. In interviews with The Times, Thornton has called the death sentence a victory. If the judge upholds it, he said, he will not have to mix with other violent criminals and will be spared potential violent attacks in prison.

Kossoris, who portrayed Thornton as a con artist and predator at trial, said he plans to file a detailed response to the defense’s 17-page motion.

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The bottom line, according to the prosecutor, is that Thornton committed “an aggravated crime that went beyond and above” most other murders.

“Most robbery murders don’t involve premeditation, taking a person to a remote spot, leaving her there so she won’t be discovered and shooting the person twice in the back and once in the chest,” Kossoris said.

But the defense motion contends that Thornton never planned to murder O’Sullivan. It says that the defendant was simply looking for a car to steal but lost control of the kidnaping and shot O’Sullivan.

The motion also describes O’Sullivan’s murder as a “terrible” crime. But states that it is not heinous enough to warrant a death penalty for the 20-year-old defendant. The death penalty is designed “for those killers who have demonstrated their callousness through the heinous nature of the murder . . . and through their history of violence.

“It is not designed for a person as immature, unsophisticated and criminally inexperienced as Mark Thornton,” the motion states.

To support their argument of jury bias, the defense attached to the motion copies of a Times photograph that shows the jury forewoman embracing a relative of the victim after the March 21 verdict.

After the verdict, jurors said they identified with O’Sullivan because she was a hard worker in her nursing job and a good parent who did nothing to contribute to her own murder.