"Lori's dead and I killed her," Hacking told his brothers, according to documents prosecutors filed Monday charging him with first-degree felony murder. The charge carries a maximum penalty of five years to life in prison.
Hacking, 28, also was charged with three counts of obstructing justice, which carries a maximum penalty of one to 15 years in prison. The obstruction charges relate to his alleged disposal of the body, the rifle and the mattress where she had been sleeping.
Lori Hacking's body has not been found, despite numerous searches of a landfill.
District Attorney David Yocom said prosecutors did not have enough evidence for an aggravated murder charge, which carries the death penalty, because they couldn't prove Lori Hacking was pregnant, as she confided to friends. They can't do so without a body.
The couple's crisis started on July 16 when Lori Hacking called the University of North Carolina at Chapel Hill to inquire about financial aid for her husband, who had told her and everyone else that he would be going to medical school there.
The couple had been planning to move there a few days later. But the 27-year-old woman was told there was no record of him even applying to the medical school. It has since been learned that he had not even graduated from the University of Utah, contrary to what he had led everyone to believe.
The following Monday, Hacking called police and reported his wife had gone jogging and never showed up for work. Authorities soon discovered he'd been busy buying a new mattress that morning, and the sheets on the bed were brand new.
They also found a bloody knife, which they believe was used to cut the mattress, and they found more blood on the headboard and in the woman's car — all identified by DNA tests as that of Lori Hacking.
Police suspect Mark Hacking used a knife to cut off the mattress's pillow top, rolled his wife's body in it and tossed it in a trash bin near the University of Utah Neuropsychiatric Institute, where he worked as an orderly.
Based on a tip, they began searching a portion of the county landfill where the trash collected the day of the disappearance would have been unloaded. Authorities said about half of the 3,000 tons of trash has been searched.
The night after he reported his wife missing, Hacking was found naked outside a hotel and was taken to a psychiatric ward, where he remained until he was taken to jail on Aug. 9. He was held on $500,000 bail, which was increased Monday to $1 million.
On July 24, he was visited by his older brothers, Scott Hacking and Lance Hacking. The brothers asked that hospital staff delay Mark's medication so he would be lucid when he talked to them. They said he confessed and they passed that information along to police.
"Everything corroborates the truth of this statement to a `T,"' Yocom said.
Hacking's attorney, Gil Athay, did not return a phone call seeking comment. He previously told Salt Lake television station KUTV that he expected to challenge the admission of the brothers' statement, and that "mental illness, mental deficiency certainly will be an issue in this case."