Peterson had divorced Savio a year before her death. His motive for killing her, prosecutors said, was fear that a pending settlement would wipe him out financially.
The glib, cocky former Chicago-area police officer seemed to taunt authorities before his arrest, once suggesting a "Win a Date With Drew Contest," and then after his arrest, a "Win a Conjugal Visit With Drew Contest." More recently, his story inspired a TV movie starring Rob Lowe.
Earlier during Thursday's sentencing hearing, Savio's family members took the stand to convey how their own lives had been shattered by the murder. Henry Savio Jr., the victim's brother, said he hoped Drew Peterson saw visions of his sister.
"I hope she is haunting him in his dreams," he said, adding later that he hoped his sister "is watching (Peterson's) descent into hell."
Another sister, Anna Doman, said she couldn't help thinking about what her sister went through in the moments before she died: "The horror and the betrayal she felt when she realized that someone she had trusted and loved more than anything was killing her."
At one point, Peterson said he'd paid for Kathleen Savio's funeral, prompting her brother to shout across the courtroom, "That's a lie!" He was ordered to leave the courtroom, and later told reporters he couldn't hold himself back.
"It was constant lies out of his mouth," he said. "So, I just erupted and had to tell him."
Prosecutors had no physical evidence tying Peterson to Savio's death and no witnesses placing him at the scene — something Peterson alluded to in his statement.
During last year's trial, they relied on typically barred hearsay — statements Savio made to others before she died and that Stacy Peterson made before she vanished. Illinois passed a hearsay law in 2008, tailored to Drew Peterson's case and dubbed "Drew's Law," which assisted in making some of the evidence admissible.
The hearsay included a friend testifying that Savio told her Peterson once put a knife to her throat and warned her, "I could kill you and make it look like an accident."
Prosecutors suspect Peterson killed his fourth wife because she could point to him for Savio's death. Peterson has maintained his fourth wife ran off with another man and is still alive.