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

Investigators believe that Lori Hacking, 27, was killed in the couple's apartment and that her body is buried under 3,000 tons of trash at the county landfill. The landfill was expected to be searched again 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," Salt Lake City Police Chief C.F. "Rick" Dinse said.

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

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

"My family and I are profoundly anguished to lose Lori," her mother, Thelma Soares, said through a spokesman. "We will grieve for her and miss her until the day we die."

Soares said her son-in-law's family "shared this double tragedy with us."

Mark Hacking had lied to relatives, including his wife, about enrolling at a medical school in North Carolina and about graduating from the University of Utah.

Investigators focused on him after learning he was at a store buying a new mattress just before reporting his wife missing.