Peterson, charged with two counts of first-degree murder in the death of Kathleen Savio, was arrested during an evening traffic stop near his Bolingbrook home and was being held on $20 million bond, Illinois State Police Captain Carl Dobrich said at a news conference.
"We are very confident in our case," Will County State's Attorney James Glasgow said.
Savio's body was found in a dry bathtub. Her death initially was ruled an accidental drowning, but authorities later said it was a homicide staged to look like an accident.
The two-count indictment against Peterson alleges that "Peterson on or about Feb. 29, 2004 ... caused Kathleen Savio to inhale fluid," causing Savio's death.
Savio's family has long voiced suspicions, saying she feared Peterson and told relatives if she died it wouldn't be an accident. Their fears resurfaced after the October 2007 disappearance of Stacy Peterson, then 23.
Drew Peterson, 55, is a suspect in the disappearance, which police have called a possible homicide, but he has not been charged. He repeatedly has said he thinks Stacy Peterson ran off with another man.
One of Peterson's attorneys, Andrew Abood, said the indictment was not a surprise.
"There was tremendous pressure for the government to do something in this case," Abood said Thursday evening. But he said one of Peterson's sons with Savio has "provided a lock tight alibi" for his father.
In an appearance on CBS' "The Early Show" last month, 16-year-old Thomas Peterson appeared alongside his father and defended him.
"I highly do not believe that my dad had murdered my mom. Because, first off, he wasn't there, he was with us during that period of time," Thomas Peterson said at the time.
Savio's 73-year-old father, however, said Thursday that an arrest was long overdue.
"I always wondered," about her death, said Henry Savio, who joined another of his daughters in filing a wrongful death lawsuit against Drew Peterson last month. "I was never pleased with the (coroner's finding of accidental drowning) from the beginning."
Drew Peterson has seemed to relish being under the media microscope since Stacy Peterson's disappearance, appearing in People magazine and on multiple national talk shows -- most recently to tout his new engagement to a 24-year-old woman.
Publicist Glenn Selig said this week that Peterson was interested in a job offer from a Nevada brothel that is the setting for the HBO reality show "Cathouse." An HBO spokeswoman said the network would sooner cancel the show than allow Peterson to appear on it.
From the day Stacy Peterson was reported missing, her husband, a cop of nearly 30 years, knew that if investigators weren't focused on him, they soon would be. Less than two weeks later, Illinois State Police called Peterson a suspect and her disappearance a possible homicide.
When authorities announced they believed the 2004 death of his ex-wife looked like it was a homicide, Peterson knew authorities were looking closely at him in that death as well.
"The husband is always a suspect, whether you declare him so or not," said another of Peterson's attorneys, Joel Brodsky, after authorities said an autopsy on Savio's exhumed body revealed she was murdered.
Savio's body was found in March 2004 by a friend of Peterson after the police sergeant called to say he was worried because he had not talked to or seen her for a few days. The couple had recently divorced.
Questions about Peterson surfaced immediately, with Savio's sister telling a coroner's jury that her sister feared Peterson and had told family members if she died that it might look like an accident but it wasn't.
Peterson married Stacy, who was 30 years younger. They had two children, who lived with the couple along with Peterson's two children from his marriage to Savio.
On the morning of Oct. 28, 2007, Stacy Peterson talked to a friend. Stacy Peterson's sister, Cassandra Cales, tried to call her in the middle of the afternoon and did not get through. Late that night, Cales went to the Petersons' home, but neither Drew nor Stacy was there. A few minutes later, she reached Drew Peterson on his cell phone and he told her Stacy had left him.
Cales didn't believe it and reported her sister missing the next day.
Slideshow archive | ABC13 wireless | Help solve crimes