Family members, investigators, clergy and even a psychic have spent weeks testifying in a northern Illinois courtroom — and Drew Peterson's murder trial hasn't even started.

Billed as a preliminary step in the case, an extraordinary hearing to determine what hearsay, or secondhand, evidence jurors will be allowed to hear during the former police officer's trial in his third wife's death has turned into a sort of legal dress rehearsal.

The testimony has exposed serious flaws in the police investigation of Kathleen Savio's death, Peterson's deteriorating relationship with his missing fourth wife and perhaps most important: a possible motive.

But none of it may matter if the judge doesn't allow at least some of the witnesses to testify during the real thing.

"If they don't get the hearsay stuff in, then they don't have a shot at this case," said Terry Sullivan, a Chicago attorney and former prosecutor.

Peterson, a brazen former police sergeant, has pleaded not guilty to first-degree murder in Savio's death. He is the only named suspect in the October 2007 disappearance of his fourth wife, Stacy Peterson, but has not been charged in that case. It was after she went missing that investigators exhumed Savio's body and determined her death was a homicide.

Almost 70 prosecution witnesses have testified during the past 3 1/2 weeks. Defense attorneys plan to begin calling about 20 witnesses next Wednesday to contradict statements made by people who said the two women feared Peterson.

"As long as they're there, it would be tough not to put in evidence that would contradict" the prosecution, said Mark Geragos, a defense attorney who is not involved in the Peterson case but has represented many high-profile clients — including Scott Peterson, the California man convicted of killing his pregnant wife, Laci.

The hearing is the result of a new Illinois law that allows a judge to admit hearsay evidence — statements not based on a witness' direct knowledge — if prosecutors can prove a defendant may have killed a witness in order to prevent him or her from testifying. The law was so closely linked to the Peterson case that some have dubbed it "Drew's law."

Prosecutors, with little physical evidence on which to base their case against Peterson, may have to rely heavily on statements that Savio and Stacy Peterson allegedly made to others. The testimony has included claims that Drew Peterson was furious Savio might get a large portion of his pension, and that Stacy Peterson suggested she could threaten to tell police that Drew Peterson killed Savio to squeeze extra money from him in a divorce.

The hearing has at times moved into areas that have little to do with hearsay. A state police investigator said he quickly decided Savio's death was an accident after her body was found in a bath tub in 2004, so he collected no forensic evidence and didn't even secure the scene. The pathologist who conducted the post-exhumation autopsy on Savio's body three years later testified that bruises and the position of her body indicated she was killed after struggling with an attacker.

The mix of those witnesses is part of a broader strategy to make the secondhand evidence more plausible and persuade the judge to allow as much as possible at trial, Sullivan said.

That's likely why much of the hearsay evidence has focused on Stacy Peterson. A minister testified that Stacy Peterson told him she was afraid of her husband and that Drew Peterson was wearing black and carrying a bag of women's clothes the night before Savio's body was found. Drew Peterson's stepbrother said he helped Peterson move a blue barrel out of his house and suspected it contained Stacy Peterson's remains.

Dozens of other witnesses provided small pieces of what prosecutors contend is a puzzle that will help jurors believe Peterson could have killed Savio.

Drew Peterson's attorneys, meanwhile, have asked about medication Savio was taking and pointed to a doctor's report that said Savio complained of dizziness. And while under no obligation to call witnesses in the hearing, they have now decided to do so.

Neither side wants to leave anything to chance, Geragos said.

Prosecutors "want to make sure that when they put evidence in ... that there's nothing that comes back to bite them," he said.

Attorneys also anticipate challenges to the state's hearsay law, perhaps to the U.S. Supreme Court.

"It's a perfect storm for both sides to have to deal with it," Geragos said.