Stacy Peterson disappeared five years ago, but the suspicions and fears she harbored about her husband haunted his murder trial and proved crucial in his conviction.

Her words came to life through two crucial witnesses who conveyed Stacy's remarks to jurors. That's hearsay evidence, or what one person tells another outside a courtroom setting.

The allowance of that evidence could possibly form the basis of an appeal by attorneys for former suburban Chicago police Sgt. Drew Peterson, 56, who was found guilty Thursday of the 2004 killing of ex-wife Kathleen Savio.

Stacy Peterson's words and her husband's conviction could also mean that he could face a new murder trial -- this time for the death of Stacy herself.

"Stacy, you are now next for justice," Savio's brother Nick Savio said after the verdict was read.

Savio was Peterson's third wife; Stacy, his fourth.

Stacy vanished in October 2007, but her body has never been found. She left three children behind at home, and her family believes she was killed.

But before Peterson can be charged again, prosecutors would have to prove that Stacy is dead and then that she was murdered.

"The longer someone is gone, the easier it is to prove they haven't just run away and that they are deceased," said James Glasgow, the prosecutor in Will County, southwest of Chicago.

"October 28, 2007, is in our rearview mirror now," he said. "We are going to look at that case and assess it as it stands today, and if we feel confident in going forward, we will be doing so."

Peterson once fueled outrage in the media with his brash behavior and flippant remarks about his wife's disappearance. But Thursday, he sat stone-faced in court as the verdict was read and returned to his jail cell as a murderer with little public sympathy.

His case, however, could live on in the court system for years.

"You know what they say, a conviction is a first step in a successful appeal," said Joel Brodsky, Peterson's lawyer.

"Believe me, there's several world-class appellate lawyers just waiting to get their teeth into this."

An appeal could be based on a number of issues, including potential prosecutorial misconduct.

But at the heart of the Peterson trial controversy is the court's allowance of Stacy Peterson's disturbing comments, which jurors said were "extremely critical" to reaching the guilty verdict.

Jurors heard what she had said through the testimony of two key witnesses: the Rev. Neil Schori, Stacy Peterson's pastor, and Harry Smith, Savio's former divorce lawyer.

Schori testified that Stacy told him she woke up in the middle of the night -- the same night that Savio was killed -- and noticed her husband was not in bed.

"After that, it was some time later, in the early morning hours," Schori said. "She saw him standing near the washer and dryer, dressed in all black, carrying a bag. She said that he removed his clothing, and then took the contents of the bag and put all of that into the washing machine."

Schori said Stacy told him that Drew told her he had killed Savio and then coached her to lie to police about it. And she did, Schori said.

Juror Teresa Mathews said Friday that the jury was troubled that police interviewed Stacy while Drew was present.

Smith testified that Stacy planned to divorce Drew and wanted to know if "the fact that he killed Kathy could be used against him" as leverage.

Just days after that phone call with Smith, Stacy disappeared.

Her statements would be struck down in most courts of law: In 2004, the U.S. Supreme Court ruled that hearsay violates a defendant's Sixth Amendment right to confront a witness testifying against him or her.

But Illinois passed a special law in 2008 that allows such hearsay evidence in rare instances when prosecutors believe a person was killed to prevent his or her testimony.