UPDATED 07/31/12 – 10:20 p.m.

JOLIET, Ill. (CBS) — Jurors in the Drew Peterson trial saw gruesome photos of alleged murder victim Kathleen Savio’s body on Tuesday, as the trial got underway in Will County.

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Peterson is accused of killing Savio in her bathtub in 2004 to prevent her from testifying against him during divorce proceedings.

CBS 2’s Mike Puccinelli reports the first day of testimony ended Tuesday evening after prosecutors called their first witness — Savio friend and neighbor Mary Pontarelli — to describe finding Savio’s body.

Pontarelli said she, her husband, her son, and another neighbor entered Savio’s home on March 1, 2004, after Peterson told her he’d been unable to contact Savio. After a locksmith opened the front door, Pontarelli said she and the neighbor went upstairs to search for Savio, while her husband and son searched downstairs, and Peterson waited at the door.

She and her neighbor found Savio curled up in the tub.

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On the stand, Pontarelli started to weep when she was shown a picture of Kathleen’s nude and lifeless body lying face down in the tub. She then recalled the moment when she ran inside the bathroom and found Savio’s body.

“I went into the bathroom and seen Kathleen. I ran out of the bathroom then, and threw myself on the ground, and started screaming,” she said.

Those screams brought Drew Peterson into the bathroom, where he took Savio’s pulse, according to Pontarelli.

“I said, ‘Drew, is she dead?’ He said, ‘Yes she is,’” Pontarelli testified.

During Pontarelli’s testimony, a picture of Savio in the tub was shown to the jurors on a video screen. Her family members were crying at the time.

Judge Edward Burmila asked that the picture be taken down after several people in the courtroom appeared to be disturbed by the image of Savio’s dead, naked body.

CBS 2’s Dana Kozlov reports the three emergency medical technicians who responded to Savio’s home on the day she was found dead will soon testify. One of those EMTs recently was arrested for drunk driving, and cut a supervision deal with prosecutors. Defense attorneys, however, will not be allowed to question him about that case.

Meantime, court officials have draped curtains along the fourth-floor hallway behind the courtroom, so that jurors cannot see Peterson wearing shackles as he is taken into court.

As for his demeanor, the former Bolingbrook cop seemed upbeat as he prepared to go on trial for allegedly killing his third wife, Kathleen Savio, in her bathtub in 2004.

After nearly three years of delays, Will County State’s Attorney James Glasgow started the trial Tuesday morning, telling jurors Peterson once boasted that “he had learned enough to kill someone and make it look like an accident.”

LISTEN: WBBM Newsradio’s Mike Krauser reports

In his opening statement, Glasgow said Drew made that boast to Stacy Peterson’s aunt in 2007. The prosecutor also told jurors that by drawing on “your common day experience from everyday life… you will be able to determine that Drew Peterson murdered Savio beyond a reasonable doubt.”

“Evidence will show he was going to kill her … she’d never make it through her divorce settlement… she would never get their children,” Glasgow said.

Glasgow also said Peterson had been abusive toward his second wife, Kathleen Peterson. In July 2002, Glasgow said, Drew Peterson broke into Kathleen Peterson’s home, pushed her down on the stairs, put a knife to her throat and told her she should just die. She said “just end this craziness,” and for some reason he pulled back, according to Glasgow.

The allegations came from a letter that Kathleen Peterson wrote, Glasgow said.

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Glasgow also began to tell jurors how Peterson offered a friend $25,000, prompting the defense to object and ask for a mistrial. The judge denied the request for a mistrial, but said Glasgow could not continue to tell jurors about Peterson’s alleged effort to hire a hitman.

During the defense team’s opening statement, defense attorney Joel Brodsky took 80 minutes to slam the state’s case, and – some would say – Savio’s character.

Brodsky said Savio slipped, fell and drowned in a household accident, and that was all there was to it.

Brodsky said a pathologist will indeed say an accidental drowning by an adult in a bathtub is rare, but “they’ll also tell you that the only thing rarer is a homicide in a bathtub.”

He also painted Savio as a bitter and manipulative liar who wanted to take Peterson for all he was worth.

“You have to ignore the myths, you have to ignore the rumor and you have to ignore the hearsay,” Brodsky said. “And when you do, you’re going to find the defendant not guilty.”

Outside court, defense attorney Steve Greenberg said prosecutors don’t have any evidence Peterson was responsible for Savio’s death, telling reporters, “They’re trying to frame him for an accident.”

Brodsky stood by his comments about Savio outside court.

“She had a very hot temper. This is not … something of dispute. Kathy Savio was described by everybody as a hellcat, a fighter,” he said.

Prosecutors weren’t discussing the case outside of court, but the spokeswoman for Peterson’s missing fourth wife, Stacy Peterson, spoke up on behalf of Savio. Pamela Bosco said Savio was being trashed by the defense during opening statements.

“I think that’s all they have to go by right now, but I think … as the trial proceeds, I think the prosecuting attorneys will show that she was a wonderful woman, and her biggest fear was what Drew was going to do to her,” Bosco said.

Before openings, the defense was addressing a motion to limit opening statements because they might be taken as evidence to jurors. The defense is concerned with hearsay statements about Savio saying she feared for her life from Peterson, which they say should not be admissible.

The judge denied the defense’s request, and called in the jury soon afterward.

A jury of seven men and five women from all walks of life will decide whether Peterson is guilty.

Peterson himself will be present in court, but will not be in shackles as he was during pretrial hearings over the past couple of years. As he was during jury selection, Peterson will be clean-shaven and wearing a suit.

The case against Peterson will not touch on the still-unsolved disappearance of his fourth wife, Stacy. He is not charged in that case.

But Stacy’s sister believes the Savio case verdict will give her family justice.

“Hopefully, after this trial, they’ll put him away and throw away the key,” Cassandra Cales said.

But Peterson’s attorney, Joel Brodsky, says not so fast. Asked if there’s a fatal flaw in the prosecution’s case, Brodsky replied: “If not having any evidence is a fatal flaw, I suppose that’s it.”

Peterson, a former Bolingbrook police sergeant, was charged May 2009 with the murder of Savio, whose body was found in a dry bathtub in March 2004.

Initially, Savio’s death was ruled an accidental drowning, but her body was exhumed after Stacy Peterson, Drew Peterson’s third wife, vanished in October 2007. After a new autopsy, officials concluded that Savio’s death was a homicide.

Prosecutors and Illinois State Police believe Stacy Peterson is dead, and Drew Peterson has been named a person of interest in her disappearance. But he has not been charged in that case.

In yet another curious twist just last week, the defense listed Stacy Peterson as a defense witness in the case, indicating a belief that she is still alive — even though her whereabouts is unknown.

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Peterson was supposed to go on trial in July 2010, but the trial was delayed as prosecutors and defense attorneys wrangled over evidence that can be allowed in court.