AR-556 Used In Boulder Shooting Bought Legally In Arvada: Police

BOULDER, CO — The man accused of shooting 10 people to death Monday at a Boulder grocery store bought a semi-automatic Ruger AR-556 pistol legally from an Arvada gun store, police said.

Ahmad Al Aliwi Alissa, 21, passed a background check before his purchase, the gun store owner said.

Alissa used the pistol to open fire at the King Soopers store, Boulder Police Chief Maris Herold said during a news conference Friday.

"The defendant was also in possession of a 9 mm handgun, but at this time, we do not believe that gun was used in this incident," Herold said.

Since the shooting, 167 people from 26 federal, state and local agencies have worked more than 3,000 hours on the investigation, Herold said. More than 150 interviews have been conducted, she said.

As of Friday, a motive for the shooting was not known, the police chief said.

"That's the focus now, and what we're trying to figure out," Herold said. "It will be haunting for all of us until we figure that out."

It's important to maintain the integrity of the investigation, despite the public's need for answers, Boulder County District Attorney Michael Dougherty said.

"If we share too much about the facts of the investigation, it's possible to see a motion by the defense to move this trial somewhere else in the state of Colorado," Dougherty said.

"I want to make sure that the people of Boulder have the opportunity [for] this trial be held, and for justice to be done, here in Boulder County."

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John Mark Eagleton, owner of Eagles Nest Armory in Arvada, said in a statement that his store was cooperating with authorities as they investigate. Alissa passed a background check conducted by the Colorado Bureau of Investigation before purchasing a gun, Eagleton said.

Alissa was charged with 10 counts of first-degree murder and one count of attempted first-degree murder. More charges will likely be filed over the next few weeks, Dougherty said.

Alissa appeared in a hearing Thursday before Judge Thomas Mulvahill in Boulder County District Court.

Alissa's attorney, Colorado public defender Kathryn Herold, requested three months to conduct a mental health assessment. Alissa is to appear before a judge in 60 to 90 days for a status hearing, but that date has not yet been set.

Alissa was treated at a hospital before going to jail. He has been moved to a jail outside Boulder County due to safety concerns stemming from threats made against him, county sheriff's spokeswoman Carrie Haverfield said in a statement Friday.

If convicted of the crimes, Alissa faces a maximum penalty of life in prison. Colorado's death penalty was repealed last year.

Boulder police Officer Eric Talley was the first officer to arrive at the store, and he was shot to death, officials said. Nine other people — including three grocery store employees — were also killed.

In addition to the 10 first-degree murder charges, Alissa was also charged with attempted first-degree murder in connection with an attempt to kill a second police officer who was called to the store, Dougherty said. That officer was not injured, the DA confirmed Friday.

Alissa's next court date is expected to be announced next week, Dougherty said.

The Associated Press contributed to this report.