JOLIET, Ill. (AP) — Authorities probing the disappearance of a police officer’s wife said Friday he is now considered a suspect in a potential homicide investigation, and that the death of an ex-wife three years ago appeared to have been staged as an accidental drowning.

Authorities received court approval to exhume the body of an ex-wife of Bolingbrook Sgt. Drew Peterson as they continued the search for his wife, Stacy, who was last seen Oct. 28.

Illinois State Police Capt. Carl Dobrich said Peterson, 53, has moved from being a person of interest in the disappearance of his 23-year-old wife to ‘‘clearly being a suspect.’’ Dobrich also said the case was now a potential homicide investigation.

‘‘We have mixed emotions right now,’’ said Pamela Bosco, Stacy Peterson’s adoptive stepmother. ‘‘We’re sad, but we needed to move on, and this is something we’ve needed to hear for a long time.’’

Drew Peterson has said Stacy Peterson phoned him and told him she had left him, and Peterson believed it was for another man. His attorney, Fred Morelli, did not immediately return calls seeking comment.

The family of Stacy Peterson, who was studying nursing at a nearby junior college, has said she feared her husband, was making plans to divorce him and would not have willingly left her children, ages 2 and 4.

The body of Peterson’s third wife, Kathleen Savio, was found in the bathtub in 2004, her hair soaked in blood from a head wound. A coroner’s jury ruled the 40-year-old’s death was an accidental drowning, even though there was no water in the bathtub. Investigators had theorized the water had drained out.

In a petition filed Friday listing the reasons authorities want to exhume Savio’s body, prosecutors said a review of evidence in the case ‘‘is consistent with the ’staging’ of an accident to conceal a homicide.’’

‘‘The one-inch gash in the back of Kathleen Savio’s head did not render her unconscious, which would have been necessary for her to accidentally drown in the bathtub,’’ the petition stated.

Prosecutors said they reviewed photographs of the crime scene and autopsy, the autopsy protocol and police reports.

Will County Circuit Court Judge Daniel J. Rozak signed the petition granting the exhumation Friday. It was not immediately clear when the body would be exhumed.

No charges were filed in Savio’s death, but ‘‘at the very least, her death should have been ruled ’undetermined,’’’ Will County Coroner Patrick O’Neil said earlier this week.

Savio’s niece, Melissa Marie Doman, said relatives have long suspected that Savio didn’t drown accidentally.

‘‘I am all for it, along with the rest of my family, because something just was never right,’’ said Doman. ‘‘I can’t really say who, but someone did something. I don’t think it was an accident.’’

Savio had gotten an order of protection in 2002, alleging a pattern of physical abuse and threats, according to court records. Drew Peterson has denied involvement with his ex-wife’s death.