Salt Lake City ? A man whose credibility began crumbling the day he first reported his pregnant wife missing was arrested Monday in her death, just before his scheduled release from a psychiatric ward.

Investigators believe Lori Hacking, 27, was killed in the couple’s apartment and that her body was buried somewhere below 3,000 tons of trash at the county landfill. The landfill search was expected to resume Wednesday.

Her husband, Mark Hacking, reported her missing July 19. He was hospitalized when he was seen running around naked outside a motel where he had taken a room, hours after making an emotional appeal on television that day for help in searching for her.

Although Lori Hacking’s body has not been found, police said they had gathered enough evidence, including the murder weapon, to bring charges against her husband.

“The evidence gathered strongly indicated Lori was the victim of a homicide and that Mark Hacking is the individual responsible,” said Salt Lake City Police Chief Rick Dinse.

Mark Hacking, 28, has not been formally charged. Prosecutors have 72 hours to file charges, but they could ask for an extension if necessary.

Dinse said police had no proof that Lori Hacking was five weeks pregnant, as she had told friends and relatives. He said if a body was found and the pregnancy was confirmed, prosecutors could add a murder charge later.

Detectives identified a motive and have found the weapon that killed Lori Hacking, Dinse said. He declined to elaborate.

Both Dinse and the Salt Lake County District Attorney’s Office said failing to find the body would not hinder the case.

The couple’s families were alerted to the arrest before Dinse’s public announcement.

“They’re devastated, both sides of that family,” he said.

Since the day his wife was reported missing, Mark Hacking’s credibility has eroded amid revelations that he lied to his wife about enrolling at medical school in North Carolina and about graduating from college.

Hacking made no admission of guilt at his arrest and is on a suicide watch, Dinse said.