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The Denver man accused of opening fire inside of a Walmart, killing three people in what police say was an act of "mass chaos," could face life in prison or even the death penalty, a judge said Friday.

Scott Ostrem, 47, made his first appearance in an Adams County courthouse dressed in a blue jumpsuit and giving one word responses to the judge.

Although prosecutors asked for more time to consider multiple counts against Ostrem, they were ordered to file formal charges by Monday. Until then, he is being held without bond on an initial warrant of three counts of first-degree murder.

Police in the Denver suburb of Thornton have provided no motive for why Ostrem walked calmly inside of a Walmart on Wednesday night and allegedly fired at random. He fled amid the panic, sparking a manhunt, and was captured the following morning about a half-mile from his home.

The victims were identified as Carlos Moreno, 66, of Thornton, and Victor Vasquez, 26, of Denver, both of whom died at the scene, and Pamela Marques, 52, of Denver, who died at the hospital.

The affidavit in the case remained sealed Friday.

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Related: Walmart Shooting Suspect Arrested Following Manhunt

While police released little information about Ostrem, neighbors at the Samuel Park Apartments described him as a loner who would walk around carrying weapons.

"He didn't seem to have anybody," Teresa Muniz, one of his neighbors, told The Associated Press. "Being angry all the time. That's what he seemed like, always angry."

Muniz said most of the building's tenants talk to one another, but Ostrem never returned her greetings and swore at people for leaving laundry in communal machines. She also said she sometimes saw Ostrem carrying a shotgun or a bow and set of arrows to and from the building.

Another neighbor, Gerald Burnett, 63, said he was sitting on the stairs outside drinking coffee one morning when Ostrem came down, told him to move and cursed at him.

"Dude had an attitude, big time," Burnett said. "He's the type of person if you said, 'Good morning,' he wouldn't say nothing."

Another resident, Dennis Valenzuela, told NBC affiliate KUSA that he noticed Ostrem treated tenants differently because of their race. Thornton is about one-third Hispanic or Latino.

"Very quiet, but verbally abusive toward Hispanics," said the 49-year-old maintenance worker. "Just real rude, he would use vulgar language with Hispanics and stuff like that."

Thornton police spokesman Victor Avila wouldn't say if investigators knew about neighbors' statements or whether race played a role in the shooting, but told NBC News that the case is "an active investigation and everything will be looked at."

Ostrem recently had financial problems and filed for Chapter 7 bankruptcy in 2015. He also had minor run-ins with police dating back to the 1990s.

For the past three years, he worked in the metal fabrication shop of a roofing company. On the morning of the shooting, he left his work station without any explanation and never came back, boss David Heidt told the AP.

"We're all bewildered as to where we are now," Heidt said.