Mark Hacking (search) told a "reliable citizen witness" in the psychiatric ward that he killed his pregnant wife as she slept, according to a probable cause statement released Tuesday by the Salt Lake County Sheriff's Department.

He told the witness he then threw Lori Hacking's (search) body in a garbage can, according to the statement.

Authorities file a probable cause statement with a court to provide reasons for continuing to hold a possible defendant in custody.

The statement also says investigators found human blood on a knife in the bedroom of the couple's apartment and on their bed's headboard and a bedrail.

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

The 27-year-old assistant stockbroker has not been seen since late July 18. Mark Hacking, 28, reported her missing the following day, telling family, friends and police that she failed to return from a morning jog at a park near downtown.

Cracks soon emerged in Mark's timeline and overall credibility, and police later said it was likely Lori never made it to the park.

FOX News on Monday obtained a surveillance video from the Maverik convenience store taken at approximately 1:30 a.m. July 19 — the same day Lori was reported missing.

Mark Hacking is seen inside the store, where he repeatedly checked his hands, pulled something out of his watch and apparently avoided eye contact with other customers.

Click here to view the surveillance video.

Hacking was arrested Monday on a charge of aggravated murder, but has not been formally charged. A judge set Hacking's bail at $500,000, according to Salt Lake County District Attorney David Yocum.

Cadaver dogs were to continue the landfill search for Lori's body Wednesday night, Yocum said at a press conference Tuesday.

But if her body is not recovered, "we will proceed without the body as a piece of evidence," he said.

"We want to make a thorough review of the case before we make a decision as to what [charge] to file," Yocum said. "Until we do we'll be unable to speculate on the strength of the case."

He said he asked police to conduct more witness interviews and type up their transcripts.

Yocum acknowledged with a "yes" that his office takes into consideration the wishes of victims' family members when deciding whether to pursue the death penalty in a murder case.

He said if his office needs more than 72 hours required by law to file charges against Hacking, he'll ask for an extension.

According to the county's three-page statement:

Police found a mattress in a trash bin near the Hackings' apartment that matched the serial numbers of the box spring recovered from inside the apartment.

The statement said Mark Hacking first called police at 10:07 a.m. on July 19 to say that his wife did not return from a jog. A few minutes later he called Wells Fargo and told his wife's co-workers that he found her car in Memory Grove park and that he was there looking for her.

Police got a receipt from the Bradley Sleep Center store, about 3 miles south of the park, showing he was buying a mattress at 10:23 a.m.

Fox News' Kathleen Wereszynski and The Associated Press contributed to this report.