08/10/2004 at 08:00 AM EDT
Massage therapist Amber Frey, the mistress of double-murder suspect Scott Peterson, is expected to take the stand in his trial Tuesday, according to her attorney, Gloria Allred.
Prosecutors have pointed to Frey as the motivation for Scott's alleged killing of his pregnant wife Laci – and Allred tells PEOPLE that Frey is nervous about being the prosecution's star witness.
"I don't think anybody would want to trade places with her," says the attorney. "She knows that many millions of people will see her and review her looks and her actions and will talk about every word she says."
Despite her nerves, Allred says Frey is ready to face Peterson. "She is going to testify," Allred insists. Will Frey look at Peterson when she takes the witness stand? "She will do what is appropriate."
Allred believes her client will be on the stand for "a considerable amount of time."
Also due to be revealed on Tuesday is recently discovered evidence that Peterson's defense attorney Mark Geragos has called "potentially exculpatory" in that it could point suspicion away from his client.
Last Thursday, Judge Alfred A. Delucchi declared a two-day halt to the case so the defense could investigate the evidence.
Prosecutors allege Peterson killed his wife in their Modesto, Calif., home on or around Dec. 24, 2002, then drove to San Francisco bay and dumped her weighted body from a small boat he had purchased just weeks earlier.
The badly decomposed remains of Laci Peterson and the couple's fetus washed ashore in April 2003, not far from where Peterson said he launched a solo fishing trip the day she vanished.
Scott Peterson, 31, has pleaded not guilty.