California prosecutors will offer immunity to Juror No. 7 in the 2004 murder trial of Scott Peterson as the convicted wife killer seeks to have his case overturned.

Peterson was convicted of killing his pregnant wife, Laci Peterson, and their unborn son, then dumping them in the San Francisco Bay on Christmas Eve in 2002. They washed up separately months later. 

Richelle Nice is expected to testify at a Feb. 25 hearing as part of Peterson’s appeal. His lawyers accuse her of lying on a jury questionnaire ahead of the high-profile trial, alleging she had an ax to grind as a woman who had also faced domestic violence while pregnant.

Prosecutors will grant her immunity so she can testify freely without the risk of self-incrimination, Stanislaus County District Attorney Birgit Fladager announced Monday. Without immunity, Nice said she would invoke her Fifth Amendment right to remain silent.

"We are pleased to know that Ms Nice will be granted immunity," Pat Harris, an attorney for Peterson, told Fox News Tuesday. "We sincerely hope that Ms. Nice will tell the full truth, and we believe that she will."

FILE - In this Dec. 13, 2004, file photo, Juror number 7, Richelle Nice, adjusts her hair as members of the jury speak with the media in the Old San Mateo County Courthouse in Redwood City, Calif. (AP Photo/Lou Dematteis, File)

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"It’s the defense’s last chance of getting the conviction thrown out now that they’ve exhausted all appeals and collateral attacks based on the facts," said Neama Rahmani, a Los Angeles-based attorney and former federal prosecutor. "They’ve already succeeded on getting the death penalty overturned, so a new trial would be a huge setback for Laci, Conner, and justice for their murders."

Peterson originally received a death sentence in 2005 – but in December a resentencing changed that to life without parole.

Scott Peterson listens to Stanislaus County Deputy District attorney Dave Harris speak during a hearing at the San Mateo County Superior Court in Redwood City, Calif., Dec. 8, 2021. (Andy Alfaro/The Modesto Bee via AP, Pool  |  getty Images)

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In her jury questionnaire, Nice denied having been the victim of a crime or having been involved in a prior lawsuit, according to Peterson’s defense team. But they say she hid the fact that she had been beaten while pregnant by a boyfriend in 2001 and that another occasion, pregnant with a different child, she obtained a restraining order against a boyfriend’s ex – which Peterson’s lawyers say amounts to a type of lawsuit.

Peterson's lawyers contend that Nice’s status as a domestic violence survivor biased her in the case and that she purposely tried to get onto the jury.

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"I don’t think you can make a cogent argument that somebody who is pregnant and has been the victim of violence can go into a trial and at the very least not feel some bias towards a circumstance where a victim is a pregnant woman who basically had violence occur," Harris told reporters Monday after a hearing.

Nice has denied their claims.

"I did not lie to get on this trial to fry Scott," she told the Modesto Bee in 2017.

The fact that prosecutors will offer immunity could mean that they believe she did not perjure herself and that Peterson’s conviction will stand, Rahmani said.

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"Reading the tea leaves, it is a sign that the prosecution believes Nice won’t provide testimony that will overturn Peterson’s conviction," he said. "The state does not have to grant her immunity."

However, if she admits to lying, the court will have a chance to decide whether she could have been fair and impartial, Rahmani added.

Peterson’s fate rests on that chance.

The Associated Press contributed to this report.