She loomed over Drew Peterson's murder trial, though her disappearance and the suspicion that the former Illinois police officer killed her was never mentioned in front of the jury.

But after a jury Thursday found Peterson guilty of first-degree murder in the 2004 death of his third wife, Kathleen Savio, his fourth wife, Stacy Peterson, now takes center stage.

"We are going to aggressively review that case with an eye towards potentially charging it," Will County State's Attorney James Glasgow told reporters outside the Joliet courthouse shortly after jurors convicted Drew Peterson of killing Savio.

Peterson, 58, was only charged in Savio's death after Stacy Peterson vanished in 2007. She is presumed dead -- though her body has never been found. Her husband is a suspect in her disappearance but has never been charged in the case.

Stacy Peterson's sister, in court to hear the guilty verdict Thursday, sounded optimistic that charges in her sister's case would soon follow.

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"He'll be charged. It'll come," Cassandra Cales said.

Savio family was as relieved and excited Thursday as Stacy Peterson's family was hopeful. As she stepped out of the crowded courtroom minutes after the verdict, Savio's sister, Susan Doman, threw herself into the arms of her husband.

"Finally, finally, finally," Mitch Doman, Savio's brother-in-law, said as he and his wife cried. Seconds later, he looked up at a reporter and said with a smile, "We finally got that murdering bastard!"

Glasgow drew cheers from the crowd gathered outside the courthouse.

"He was a thug," Glasgow said of Peterson, his voice rising in indignation. "He would threaten people because he had a gun and a badge. Nobody would take him on, but we took him on and he lost."

As Glasgow prepares for a Nov. 26 sentencing hearing for Peterson -- during which he is certain to ask the judge to impose a sentence close to the maximum 60-year prison term -- he strongly hinted that many of the things he was forbidden from saying in front of the jury about Stacy Peterson's 2007 disappearance will be part of his presentation.

Among evidence prosecutors could present at sentencing is that Stacy Peterson, like Savio before her, feared Peterson might kill her. Then there was a man, Thomas Morphey, who testified at a 2010 hearing that he helped move a blue barrel that he later came to believe contained the body of Stacy Peterson.

Stacy Peterson's disappearance was the reason Glasgow's office reopened the investigation into Savio's death, which ultimately led to Peterson's conviction Thursday. Glasgow's office long has maintained that Stacy Peterson did not just leave on her own and that they not only believe she is dead but that Drew Peterson killed her.

Glasgow said that the case against Peterson in his fourth wife's death is getting nothing but stronger.

"The longer any person is gone, the easier it is to prove that they haven't just simply run away, that they are deceased," he said. "Oct. 27, 2007, (when she disappeared) is way in our rearview mirror."

Peterson's attorneys promised to appeal his conviction, partly because of the reliance on hearsay evidence. It not only included Savio's family members testifying that she feared Peterson would kill her and make it look like an accident. It also included testimony from Stacy Peterson's pastor and a divorce attorney about comments Stacy Peterson made that she believed her husband killed Savio.

"It's a dark say in America when you can convict somebody on hearsay evidence," said Joe Lopez, one of Peterson's attorneys.

Attorneys suggested they will fight the conviction on two fronts. First, they contend that the judge allowed hearsay evidence he should have been barred even under the new state law. Second, they said they will fight the law itself.

"The law has to be challenged," said Ralph Meczyk, another of Peterson's attorneys. "It's the appellate court now, and it should go to the Illinois Supreme Court. Our belief is that it does violate the 6th Amendment," which details the rights of criminal defendants.

Meczyk said the U.S. Supreme Court has "ruled on the issue" but that the Illinois Supreme Court "does not have to follow in lockstep."

Glasgow, though, said he isn't worried about an appeal.

"They're absolutely wrong," he said about the defense attorneys. He said federal law is clear and has been upheld around the country and state law is solidly in his corner.

"If you murder a witness to silence them, you extinguish your right to confront the witness," he said.

Whatever happens, Thursday's verdict was a stunning latest chapter in a saga that has been the stuff of tabloids and cable television in the five years since Stacy Peterson disappeared.

It was then -- after the fourth wife of the police officer, 30 years her senior, vanished -- that authorities reopened the investigation into the death of Savio, whose body was found in a dry bathtub three years earlier.

While search teams were scouring the woods lakes and even construction sites near Peterson's Bolingbrook home, Glasgow's office was moving to exhume Savio's body -- an exhumation that led authorities to determine that her death was not an accident as originally determined, but a homicide.

The trial was the first of its kind in Illinois history, with prosecutors building their case largely on hearsay thanks to a new law, dubbed "Drew's Law," tailored to Peterson's case. That hearsay, prosecutors had said, would let his third and fourth wives "speak from their graves" through family and friends to convict Peterson.

Hearsay is any information reported by a witness that is not based on direct knowledge.

One after another, witnesses told jurors that Savio told of being threatened by Peterson, that she feared for her life and slept with a knife under her mattress out of concerns that Peterson would follow through threats and kill her.

During the trial -- as Peterson sat quietly, his face never betraying any emotion -- witnesses testified about how Savio's body was discovered by a neighbor March 1, 2004. She was face down in her dry bathtub, her thick, black hair soaked in blood and a 2-inch gash on the back of her head.

Defense attorneys presented their own experts to counter pathologists who told jurors Savio's death was no accident. Her death, they said, was an accident in 2004 and it remained an accident in 2012.

Jurors heard that Peterson had divorced Savio a year before her death and, according to prosecutors, killed her out of fear that a pending settlement, which included their $300,000 home, a tavern they both owned and Peterson's police pension, would wipe him out financially.

With Peterson often acting glib and cocky during the investigation -- seeming to taunt authorities, even suggesting a "Win a Conjugal Visit With Drew" contest on a radio show after his 2009 arrest -- the case was tabloid fodder from the start and even was turned into a TV movie starring Rob Lowe.

What jurors did not hear or see was any physical evidence tying Peterson to Savio's death. Nor did they hear from any witnesses who placed Peterson at the scene at the time of Savio's death, or even an exact time she died or how Peterson might have drowned her.

Savio's brother mentioned Stacy Peterson as he read a statement from the family outside court after Thursday.

"Stacy, you are now next for justice," Nick Savio declared as he finished speaking.