Soon after authorities believe Mark Hacking (search) killed his wife, he is seen inside a convenience store, where he repeatedly checked his hands, pulled something out of his watch and apparently avoided eye contact with other customers.

His early morning trip to the Maverik convenience store is captured in a surveillance video, obtained exclusively by FOX News. The tape was taken at approximately 1:30 a.m. Monday, July 19 — the same day Mark's wife Lori Hacking (search) was reported missing.

Click here to view the surveillance video.

Mark Hacking told police he was asleep at that time, according to sources. The Maverik convenience store lies a few blocks from the Hackings' apartment.

In the video, Mark Hacking, alone and dressed in hospital pants, enters the store and walks down the candy aisle in an apparent attempt to steer clear of another patron. He then approaches the clerk's counter, where he buys a pack of lime-flavored Camel cigarettes, sources say.

Mark and Lori Hacking went to the same store together at around 9:30 p.m. earlier that Sunday, according to reports. Many believe that was the last time Lori was seen alive.

During that first trip to the store, Mark Hacking was wearing shorts and bought soda. He gestured to the clerk, named Eric Holleman, in an apparent signal asking him not to tell his wife he buys cigarettes, since the clerk mentioned to Lori Hacking that he sees him in the store all the time.

Holleman was not the clerk on duty when Mark Hacking returned alone at 1:30 a.m.

FOX News obtained the video following Monday's announcement that police arrested Mark in Lori Hacking's death, just before his scheduled release from a psychiatric ward.

Investigators believe Lori Hacking, 27, was killed in the couple's apartment and that her body is buried somewhere below 3,000 tons of trash at the county landfill. The landfill was expected to be searched again Wednesday.

A July 19 preliminary police report obtained by the The Deseret News says officers went to the apartment to maintain security just hours after Lori was reported missing.

Just as one officer arrived, he noticed Mark Hacking walking out "holding two cell phones, a small tin container, a blue cloth and a lighter," according to the police report referred to by The Deseret News in its Tuesday edition.

Mark Hacking 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 yet 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," said Salt Lake City Police Chief Rick Dinse (search).

Mark Hacking, 28, has not been formally charged. Prosecutors had 72 hours to file charges from Monday's arrest, but they could ask for an extension if necessary.

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 second murder charge later.

Detectives identified a motive and have found the weapon that killed Lori Hacking, Dinse said. He declined to elaborate.

Both Dinse and the Salt Lake County District Attorney's office said failing to find the body would not hinder the case.

Since the day his wife was reported missing, Mark Hacking's credibility has eroded amid revelations that he lied to his family about enrolling at medical school in North Carolina and about graduating from the University of Utah.

Hacking made no admission of guilt at his arrest and is on a suicide watch, Dinse said. Hacking was picked up before his scheduled release Monday from a psychiatric ward at the University of Utah Hospital.

Dinse said Mark Hacking's 13-day hospitalization gave detectives more time to investigate. Mark Hacking's lawyer refused comment Monday.

Lori Hacking, an assistant stockbroker, has not been seen since late July 18. Mark Hacking 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 the husband's timeline and overall credibility, and police later said it was likely that Lori never made it to the park.

Her car was found at the park July 19, and Dinse said police recovered evidence from it, but would not elaborate. Other evidence included items taken from the apartment and a nearby trash bin.

Investigators focused on Hacking after learning he was at a store buying a new mattress just before reporting his wife missing. Authorities were later seen removing a box spring from the couple's apartment. Investigators have refused to confirm reports that they found a mattress in a nearby trash bin.

The family issued a statement Saturday saying information Mark Hacking had provided made further volunteer searches for Lori Hacking unnecessary. The family also relayed information from Mark Hacking that indicated further search efforts should be concentrated at the landfill.

The family's statement did not say what Mark Hacking had told his relatives, and Dinse would not elaborate Monday.

The Associated Press contributed to this report.