Lori Hacking was reported missing July 19. Her husband said she went jogging that morning in Memory Grove and City Creek Canyon but never returned home. Her car was later found parked in front of the gate to Memory Grove.

But almost from the beginning questions were raised about Mark Hacking and his alleged time line. It was learned that Hacking dropped out of college in 2002 even though he told his family he had graduated. He also told them he had been accepted to medical school in North Carolina even though he never applied.

On the day Lori disappeared, Mark went to two different stores to buy a mattress but told police he was searching City Creek Canyon for Lori and jogged the three-mile trail twice looking for her.

Police later said they believed Lori never went jogging that day.

Hacking had been in the University of Utah psychiatric ward since the early morning hours of July 20 when he was found running naked and creating a disturbance in front of the Chase Suite Hotel, 765 E. 400 South.

Dinse said with the pending release of Hacking from the hospital Monday his investigators made the decision to arrest him. Detectives actually had enough evidence to arrest him sooner, Dinse said, but with Hacking in the hospital it gave detectives more time to collect evidence.

Hacking's attorney, D. Gilbert Athay, was made aware of the pending arrest before Mark was picked up by officers, Dinse said. Athay had no comment Monday.

Police remained tight-lipped Monday regarding details in the case and what type of evidence was collected, including the alleged murder weapon.

"We do believe we know the weapon that was used" was all Dinse would say.

The Deseret Morning News first reported that a knife with blood and hair samples was seized as evidence from the apartment.

Dinse also did not openly speculate Monday about a possible motive for the killing, saying only that "we believe we understand the motive."

He also added that Hacking had not made any type of confession.

Neither Lori's nor Mark's families attended Monday's police news conference. Dinse said the families had known for a while the direction the investigation was taking and were notified earlier Monday of the arrest.

"They were devastated. Both sides of the family," Dinse said.

Although Lori's body has not been recovered, Dinse said he was "confident we have a good case here."

"We believe this case is strong enough that we could prosecute without (a body)," Dinse said.

The fact Lori was five weeks pregnant did not play a factor in deciding to arrest Hacking for aggravated murder, Dinse said. He did not say, however, what any aggravating circumstances were.