BOLINGBROOK, Illinois (CNN) -- The disappearance of a suburban Chicago police sergeant's wife is now being treated as a potential homicide, and her husband is a suspect, authorities said Friday.
In another development, a judge signed an order to exhume the body of Drew Peterson's third wife, who was found drowned in a bathtub in 2004, said Will County State Attorney James Glasgow.
Peterson, 53, said he last spoke to 23-year-old Stacy Peterson -- his fourth wife -- the night of October 28.
Drew Peterson initially told the media he believed his wife ran off with another man, but he hasn't repeated that accusation. CNN has been unable to contact Drew Peterson for comment.
The couple have been married four years and have two children, who have been interviewed for the investigation, Glasgow said. Drew Peterson also has older children from a previous marriage.
Investigators have twice searched the couple's home and vehicles, and removed several items, including computers, said Illinois State Police Capt. Carl Dobrich.
Drew Peterson allowed a limited search on the night his wife was reported missing, but investigators were not allowed to look throughout the entire house and were given access to only one of the vehicles at that time, Dobrich said.
"Early on, we looked at this as a missing persons case, but also believed strongly ... it was strongly starting to look at Drew Peterson as being a person of interest," Dobrich said.
"I would say that right now, Drew Peterson has gone from being a person of interest to being a suspect."
New information turned up during the investigation also raised questions about the death of Peterson's third wife, Kathleen Savio, which was ruled an accident by a coroner's jury, Glasgow said.
"There are strong indications that it was a homicide," he said. "That's why we are doing the exhumation, because there are tests that need to be done that weren't done during the first autopsy." Watch why authorities want to exhume the body »
Glasgow cited abrasions on Savio's body and a gash on her head that could not be readily explained.
"Our main thrust is to determine whether or not it was a homicide, and as we do that, we will see if there is any evidence that implicates anyone," he said.
Glasgow, who was not state attorney at the time of Savio's death, said he reviewed the case file before deciding to reopen the case.
"With 29 years of experience, there was no doubt in my mind it wasn't an accident," he said. "That was clear."
In 2002, Savio was charged once with battery and once with domestic battery against her husband, but was found not guilty at trial, Glasgow said.
Another time, she tried to bring domestic battery charges against Peterson, but no charges were ever filed.
Savio's sister, Sue Doman, said Savio expressed fear of Drew Peterson.
"She told me all the time, 'He's gonna kill me. It's gonna look like an accident,' " Doman said.
Doman said she didn't believe her sister could have died in the way the investigation concluded.
"I don't understand accidental drowning. You just don't drown in the bathtub, especially a small whirlpool. You just don't do that," she said.
Meanwhile, friends and family of Stacy Peterson said she expressed concerns about her husband.
A friend, Steve Cesare, has told CNN he received e-mail from her describing her relationship as abusive.
The woman's aunt, Candace Aikin, of El Monte, California, said Stacy Peterson confided in her that there were problems during a visit to the Peterson home in suburban Chicago last month.
"She said that she was afraid because he was following her around 24/7, even inside the house," Aikin said.
"He was very obsessed and stalking her, even inside her house. She was very, very full of stress and just not happy in her marriage at all," Aikin said. E-mail to a friend