Poll Finds Most Believe That Thornton Is Guilty of Slaying : Courts: In change-of-venue request, defense says 66% believe that the teen-ager killed a Westlake nurse. Prosecutors oppose any move.

Two-thirds of Ventura County’s registered voters believe that accused killer Mark Scott Thornton murdered Westlake nurse Kellie O’Sullivan in September, according to a poll aimed at getting the trial moved to another county.

The poll, made public Monday as part of a defense change-of-venue request filed in Superior Court, says 85% of the county’s voters have some awareness of the slaying and another 66% believe that Thornton is guilty of murder.

“It is apparent that this case has become embedded in the collective memory of the residents of Ventura County, making it impossible for Mark Scott Thornton to receive a fair and impartial trial,” Deputy Public Defenders Howard J. Asher and Susan R. Olson said in the motion.

Police say Thornton, 19, kidnaped and fatally shot O’Sullivan, 34, during a carjacking. A grand jury Dec. 6 indicted the teen-ager, charging him with kidnaping and murder under special circumstances, which could send him to the gas chamber. Prosecutors plan to oppose a change of venue. Deputy Dist. Atty. Peter D. Kossoris said prosecutors are arranging to have their own public opinion poll on the matter.

The change-of-venue papers were filed Friday. But they were kept from the public until Monday, when Superior Court Judge Charles R. McGrath agreed to allow the public to inspect them.

Other records in the case, including a transcript of grand jury testimony, have been sealed. At the request of The Times and Ventura County Newspapers, McGrath has said he will release them--but not until after he rules on the motion June 6.

Public defenders also said Monday that they plan to ask the judge to throw out Thornton’s indictment because the district attorney’s office helped screen the grand jury that indicted him.

District attorney investigators have historically conducted background checks on prospective grand jurors.

But Asher and Olson said those background checks became much more extensive two years ago when a new law gave the grand jury power to hand out indictments in criminal cases. Previously, the grand jury only investigated political corruption and government inefficiency.

Since 1990, the grand jury has delivered indictments in 99 cases, compared with only a handful of such indictments during the 1980s, court documents show.

This is the second time defense attorneys have cited alleged problems with grand jury selection in an attempt to have charges dismissed against Thornton. A judge refused earlier to grant public defenders access to grand jury records after they claimed that the panel did not include enough Latinos.

Both Thornton and his alleged victim are white.

“I think in a case like this, they are going to try to raise everything they can,” Chief Deputy Dist. Atty. Kevin J. McGee said.

As for the change-of-venue request, Asher said more people in Ventura County seem aware of the Thornton case than many other high-profile crimes in recent years.

The random, scientific public opinion poll was conducted by the Social Science Survey Center at Cal State Chico. It involved telephone interviews with 403 registered voters in the county and had a margin of error of about 3%.

Asher said that moving the case to another location would save Ventura County time and money in trying to seat an impartial jury for Thornton’s trial locally.

He said that only one-third of the voters in Ventura County have not decided that Thornton is guilty and that many potential jurors would have to be excused because of financial hardship or opposition to the death penalty.

The Thornton trial is expected to last four months or more.

“I don’t think trying to cure this through jury selection is going to help,” Asher said.

The defense motion said 140 news stories have been published in the county’s seven newspapers since Sept. 16, two days after O’Sullivan disappeared.