Sides Rest in Thornton Death-Penalty Hearing : Courts: Prosecutors end their rebuttal after a judge blocks further witnesses. Final arguments remain in sentencing phase of the murder trial.

After seven weeks of defense-dominated testimony, both sides in Mark Scott Thornton’s death-penalty hearing rested their cases Wednesday and began preparing for closing arguments in the high-profile murder trial.

Prosecutors abruptly ended their four-day rebuttal case after Ventura County Superior Court Judge Charles R. McGrath refused to allow them to put additional witnesses on the stand to testify about the character of the defendant.

Their last witness, one of Thornton’s former teachers, grudgingly told the jury the defendant once threatened his life at Conejo Valley High School.

“You’re going to be dead,” Al Frankfurter said Thornton told him after the teacher called the defendant’s mother about his excessive tardiness and absences.

A Superior Court jury convicted Thornton in December of first-degree murder for fatally shooting Westlake nurse Kellie O’Sullivan during a carjacking. O’Sullivan was kidnaped during midday in Thousand Oaks and driven to the Santa Monica Mountains, where she was killed.

As they left the court, grim-faced prosecutors declined to comment on the judge’s decision to exclude their character witnesses.

Earlier in the penalty phase of the trial, McGrath refused to allow them to put members of the victim’s family on the stand to talk about losing their loved one.

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As a result, prosecution witnesses testified only about four days during the trial compared to nearly four weeks of testimony from defense witnesses.

“I didn’t anticipate the entire case ending today,” said Senior Deputy Dist. Atty. Peter D. Kossoris.

Defense attorneys said they believe the jury better understands the tragedies that occurred in Thornton’s life before he killed the nurse.

“I think our case went very well,” said Deputy Public Defender Susan R. Olson. “The judge has been very fair, and he followed the law about (excluding) rebuttal witnesses.”

Both sides claimed to have strong cases to present to the jury Tuesday, when closing arguments will be heard.

Despite the relatively short prosecution case in the penalty phase, Kossoris said he believes his camp can persuasively argue that Thornton deserves to die because of the way O’Sullivan was murdered.

Prosecutors have theorized that the nurse was shot after Thornton forced her to knees under a large tree whose branches formed a cave-like grotto.

And that, Kossoris said, is reason enough for the jury to support his position.

But Olson said the jury now knows that Thornton had a tough life, which helps explain how he ended up a murderer.

The defendant has a mental deficiency and was raised by neglectful, unfit parents who were strung out on drugs during most of his childhood, the defense has suggested.

“We will summarize what went wrong with this young man’s life,” Olson said.

Ironically, the final witness was called to the stand by the prosecution, but testified that he does not want to see Thornton executed.

Frankfurter, a special-education teacher at the Thousand Oaks continuation high school, said he is fundamentally opposed to capital punishment. Frankfurter taught Thornton math, science, biology, English history and health in the defendant’s senior year.

Frankfurter said Thornton became homeless that year and slept in a car after being thrown out of his parents’ home.

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Thornton’s mother evicted the defendant from the family’s home after Frankfurter informed her that Thornton was habitually tardy and absent, the teacher testified.

But Frankfurter said he did not believe Thornton actually planned to carry out his threat. He also said Thornton frequently lied and caused trouble in the classroom.

“Did you form the opinion that he was a con artist and liar?” Kossoris asked.

“I formed the opinion that he was a con artist,” Frankfurter answered, saying, however, that he blamed Thornton’s emotional problems on his family life.