Newly unsealed search warrants in the case of the man accused of killing three guards and injuring another in an attempted robbery at the University of Alberta allege that up to $1.9 million went missing after the foiled heist.

The June 15 documents indicate that G4S -- the company that employed the guards -- claims between $600,000 to $1.9 million dollars remain missing.

Initial speculation was that hundreds of thousands of dollars were stolen.

Travis Baumgartner, 21, is accused of fatally shooting three co-workers and critically wounding another.

Baumgartner was arrested by officials at the U.S. border near Abbostsford, B.C., on June 16. At the time of his arrest, he had nearly $300,000 in his possession.

Baumgartner’s mother, Sandy, told detectives she found nearly $64,000 in cash on her kitchen table, following the robbery.

She also told detectives that just prior to the robbery she had argued with her son over rent money.

A distraught Sandy told CTV Edmonton that she deeply regrets fighting with her son.

“I felt so bad because our last words to each other were angry words, and you know like he was telling me he was never coming back,” she said. “I was just… it was one of those kinds of things where you just … there were angry words that were said and it was over something so really insignificant.”

Baumgartner was reportedly in training with G4S when the shooting occurred.

The search warrant reveals that the guards were shot while they were in a secure area that only G4S employees have access to and that all of their guns were loaded and holstered at the time of the shooting.

Based on where the victims were located and the positioning of the bullet holes, investigators believe the G4S employees were likely loading the ATM when they were shot, according to the search warrant.

Three of the guards, 26-year-old Michelle Shegelski, Eddie Rejano, 39 and Brian Ilesic, 35, died of their injuries while Matthew Schuman sustained serious head injuries during the heist.

One crime expert told CTV News that the tragic crime that took place on the University of Alberta campus was easy for police to piece together.

“It was from the get-go so quickly solvable,” said Doug King, a professor of justice studies at Mount Royal University. “They had him as a prime suspect in a couple of hours.”

Baumgartner is scheduled to make his next court appearance on Sept. 14. None of the allegations within the search warrants have been proven in court.

With reports from CTV Edmonton’s David Ewasuk and Sean Amato