The husband of a missing pregnant woman told a "reliable citizen witness" in the psychiatric ward that he killed his wife as she slept and then threw her body in a trash bin, according to a court filing.

The document, released Tuesday by the Salt Lake County Sheriff's Department, also says investigators found human blood on a knife in the bedroom of Mark Hacking's apartment and on the couple's headboard and bedrail.

Blood found in the bedroom matched traces of blood found in Lori Hacking's car, according to the statement.

Mark Hacking was arrested Monday on a charge of aggravated murder, even though his wife's body has not been found. Lori Hacking has not been seen since July 19, when Hacking said his wife failed to return from a morning jog.

Investigators believe the 27-year-old woman was killed in the couple's apartment and that her body is buried somewhere in 3,000 tons of trash at the county landfill. Searches using dogs were to resume Wednesday night.

Mark Hacking, 28, has not been formally charged. He is being held without bail and was placed on suicide watch.

While thousands of friends and volunteers turned out to search for the missing woman, police already were investigating her husband and searching the couple's apartment.

Police were seen removing a box spring — but no mattress — from the apartment. They refused to confirm that they had seized an old mattress from a nearby trash bin.

On the morning that Hacking reported his wife had disappeared, police have said, he was buying a mattress even though he told friends and authorities he had been searching her jogging route.

Two days later, news organizations discovered that Hacking had lied about graduating from the University of Utah and lied about being accepted at a medical school in North Carolina, where the couple was to have moved within just days.

Mark Hacking was hospitalized after he was seen running around naked outside a motel where he had taken a room, hours after making an emotional appeal on television for help in searching for his wife.

Lori Hacking's brother, Paul Soares, told "The Early Show" on CBS on Tuesday that the situation is unimaginable.

"It's been described as surreal and that's really how we feel: a situation that you just can't believe is happening," said Soares. "It does come as a shock to me because we did know Mark for so long. But, at the same token, you just don't know what someone's capable of."

Lori Hacking had told friends that she was five weeks pregnant, but police said she had not confirmed a home pregnancy test by visiting a doctor. If her body is found and the pregnancy is confirmed, prosecutors could add an additional murder charge.