MODESTO - Controversy continued to swirl Wednesday around a now-questioned student survey cited by defense lawyers in a successful bid to move Scott Peterson's murder trial.

At the request of prosecutors, Judge Marie Silveira ordered California State University professor Stephen Schoenthaler to appear in court Tuesday to discuss the validity of surveys students have said were a fraud.

The Cal State Stanislaus professor has been under fire from prosecutors, who want to talk to students who told the Modesto Bee they lied on a class project documenting public opinion.

Wednesday's hearing focused on a defense request to toss an order holding Peterson, 31, on murder charges -- which Silveira denied -- but prosecutor David Harris zeroed in on the survey.

"What we have to do is find out who these students are and verify their stories," Harris told Silveira. "I think that goes to the very merits of what we're trying to do here, which is search for the truth."

Harris issued a subpoena ordering Schoenthaler to attend Wednesday's hearing and produce documents relating to what he said was a class project. Silveira declined Harris' request to order Schoenthaler to turn over the information, saying she was assigned only to review the motion to dismiss the holding order.

In that matter, Silveira said she was not allowed to rule on the strength or weakness of the evidence. Instead, she was charged with deciding if evidence presented at the November preliminary hearing generated "reasonable suspicion" Peterson had killed his wife and unborn child, she said.

The evidence was sufficient, Silveira said, to back the holding order.

Defense attorney Mark Geragos had argued police wrongfully focused on Peterson from the moment his wife, Laci Peterson, was reported missing Dec. 24, 2002. Investigators and later prosecutors refused to review other viable theories, he said.

He pointed to autopsy results indicating her fetus was three to seven weeks older than it was when she vanished. That indicated she was still alive after being reported missing, he said, and while her husband was under extensive police scrutiny.

The case has attracted massive media attention from the beginning, which intensified when the remains of Laci, 27, and those of the couple's unborn son washed ashore in Richmond in April. Peterson, who said he was fishing on the San Francisco Bay when his wife vanished, was arrested April 18 and charged with two counts of murder and special circumstances.

Hundreds of articles and countless TV and radio broadcasts led Judge Al Girolami last week to move the trial from Stanislaus County. He said his decision also was based on -- albeit minimally -- defense surveys of potential jurors.

Two defense surveys showed Peterson probably could not be tried before an impartial jury in Stanislaus County.

Paul Strand, a San Diego State political science professor, said 98 percent of the 301 people in his poll said they had heard of the case. Nearly 60 percent of respondents said Peterson was "probably guilty" or "guilty beyond a reasonable doubt" of the charges.

Schoenthaler came forward last year with an unsolicited study of 1,175 San Joaquin Valley residents. The project also showed Peterson could not be fairly tried in Stanislaus County.

Girolami is scheduled to make a decision next week on where to hold the trial. The state Administrative Office of the Courts said Tuesday that Alameda, Orange, Santa Clara and San Mateo counties are contenders.