CHICAGO — Opening statements get under way Tuesday in the trial of a former police officer who allegedly killed his third wife -- charged only after his fourth wife disappeared under suspicious circumstances.

Drew Peterson, former police sergeant in the town of Bolingbrook, Illinois has spent the last three years in jail awaiting trial for the 2004 drowning death of his third wife, Kathleen Savio.

He also is the prime suspect -- although he has never been charged -- in the 2007 disappearance of his fourth wife, Stacy Peterson.

Her disappearance fueled a media frenzy, as people across the United States became fascinated with the young, pretty, blonde mother, married to a much older, seemingly unconcerned, police officer.

Peterson, 58, publicly commented on his missing wife's moods and menstrual cycle, and taunted authorities, who have still never found her.

The story was even turned into a made-for-TV movie, with Hollywood star Rob Lowe in the leading role.

A legacy of this intensive coverage is that jurors may already know about Stacy, her mysterious vanishing, and authorities' suspicions Peterson killed her and disposed of the body.

However, the judge in this week's trial decided the jurors will hear little about Stacy in court.

Instead, testimony will focus on Savio, who was found dead in a dry bathtub on March 1, 2004. Savio's death was initially ruled accidental, but after Stacy disappeared, authorities reopened the case and determined it had been murder.

Prosecutors argue Savio's injuries show signs of a struggle and that the timing of her death, just weeks before she and Peterson were scheduled to go to court over divorce-related property issues, was suspicious.

Peterson denies wrongdoing in both cases.

His lawyers argue there is no evidence directly linking him to the crime scene and that police interviews with witnesses were done three years after the fact. They say the death was an accident, as the coroner originally determined.