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BOISE — The alleged perpetrator of Monday's mall shooting possessed multiple firearms and ammunition, and he was known to law enforcement prior to the incident which left three people dead.

The shooter, Jacob Bergquist, 27, of Boise, died Tuesday at Saint Alphonsus Regional Medical Center. Law enforcement officials say he was responsible for a Monday afternoon shooting spree at the Boise Towne Square mall that killed two and injured four others, including a Boise Police officer. 

On Tuesday, the Ada County Coroner identified the alleged assailant along with the two people killed, Jo Acker, 26, of Caldwell, a mall security guard, and Roberto Padilla Arguelles, 49, of Rupert.

The Boise Police Department shared new details based on a preliminary investigation of Monday's shooting.

The shooter possessed multiple firearms along with ammunition, and he used a handgun both inside the mall and outside, where he exchanged gunfire with police before being apprehended, Boise Police officials said Tuesday. Investigators found 18 shell casings inside the building.

Boise Police, Idaho State Police and Boise Towne Square mall security interacted with the suspect prior to Monday, Boise Police Chief Ryan Lee said. The past interactions related to disruptive behavior, which did not warrant arrest, Lee said. 

Police have yet to identify a motive for the shooting. Local and federal law enforcement agents searched the suspect's Boise home and found items of interest, Lee said. A "multi-state effort" is underway to learn more about the shooter, said a news release.

"We've been conducting investigations related to Mr. Bergquist, looking at any social media information, any other evidence that we may have, anything to help us understand motivation," Lee said during a Tuesday news conference, streamed online by KTVB.COM. "We're still very early on in that investigation, and there's not much information that I can share relative to that."

Police have not revealed the cause of Bergquist's death, which is being investigated by the Ada County Critical Incident Task Force.

Also on Tuesday, Boise Police released a preliminary timeline of the shooting.

At 1:50 p.m., dispatch began receiving calls about gunfire in the Boise Towne Square mall. Callers said a white, male adult, dressed in black, fired multiple shots inside the building and one person was down. The shooter shot and killed Acker, the mall security guard, who confronted him on the first floor of a department store. He then fired several more rounds inside the building, striking a second victim, Padilla Arguelles, who later died at the hospital. 

The shooter continued firing within the mall, injuring two other women. The women were not named but were identified as a 52-year-old and a 23-year-old. Their injuries were non-life threatening. 

At 1:53 p.m., officers arrived and witnessed a suspect matching the shooter's description running from the area. They confronted him behind a business on the 500 Block of N. Milwaukee.

There was an exchange of gunfire between the suspect and at least one officer. An officer was shot at through the window of his vehicle and injured by glass shards. He was treated and released from a hospital. Additionally, a woman in her vehicle on Milwaukee Street was injured during the gunfight.

Officers responded to the incident about two and a half minutes after initial reports, Lee said. The chief praised officers' quick response. 

"The time frame from when he decided to engage in homicidal violence to when the police responded and interrupted him is an incredibly short timeline," Lee said. "Frankly, the courage, the willingness to step into harm's way, to risk their own lives and maybe not make it home, to protect this community is what kept this from being a more grave tragedy."

Lee also commended mall employees for sheltering patrons and shoppers and reacting quickly. 

"Those at the mall responded admirably," he said. 

An investigation into the shooting is ongoing. Boise Police is asking anyone who was a witness and has not yet spoken to police to contact the department through Crime Stoppers, by calling 208-343-2677, or online at


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