Boulder, Colorado Police Chief Maris Herold says multple law enforcement agenices have been working to determine the details surrunding the deadly supermarket shooting this week, but are still trying to determine a suspect motive. "Like the rest of the community, we, too, want to know why. Why that King Soopers, why Boulder, why Monday," Herold said during a media briefing Friday. The suspect, Ahmad Al Aliwi Alissa, bought a gun before the shooting at a local gun store after passing a background check, the store's owner said Friday. John Mark Eagleton, owner of Eagles Nest Armory in the Denver suburb of Arvada, said in a statement that his store was cooperating with authorities as they investigate the Monday shooting that killed 10 people, including a police officer. Eagleton said Alissa passed a background check conducted by the Colorado Bureau of Investigation before purchasing the firearm. Alissa was convicted in 2018 of misdemeanor assault after he knocked a fellow high school student to the floor, climbed on top of him and punched him in the head several times, according to police documents. He was sentenced to probation and community service. Colorado has a universal background check law covering almost all gun sales, but misdemeanor convictions generally do not prevent people from purchasing weapons. If Alissa had been convicted of a felony, his gun purchase would’ve been prohibited under federal law. According to the arrest affidavit, Alissa bought a Ruger AR-556 pistol — which resembles an AR-15 rifle with a slightly shorter stock. According to two law enforcement officials, Alissa was born in Syria in 1999, emigrated to the U.S. as a toddler and later became a U.S. citizen. He would need to be a citizen to buy a gun. The officials were not authorized to speak publicly and spoke to The Associated Press on condition of anonymity. An AR-15-style gun recovered inside the supermarket was believed to have been used in the attack, said a law enforcement official briefed on the shooting who was not authorized to speak publicly and spoke to the AP on condition of anonymity. Alissa made his first court appearance Thursday. His public defender asked for the mental health evaluation but provided no details about Alissa's mental health. The suspect’s next hearing will not be scheduled for two to three months to allow his defense team to evaluate his mental state and evidence collected by investigators. He is charged with 10 counts of first degree murder and one count of attempted murder for allegedly shooting at a police officer who was not hurt. Among those slain was Boulder Police Officer Eric Talley, 51, who was the first officer to arrive on the scene, according to Boulder police Chief Maris Herold. Boulder County District Attorney Michael Dougherty said Friday that additional charges of attempted murder in the first degree will be filed "in the very near future." Alissa entered court in a wheelchair, presumably because of a gunshot wound to the leg that he suffered in an exchange of gunfire with police at the King Soopers grocery. Before his court hearing, Alissa was last seen handcuffed and being led out of the supermarket by police on Monday. He had removed all clothing except his shorts before being taken into custody, and his leg was bloody. A rifle, a green tactical vest and a handgun were recovered inside the grocery store, according to the arrest affidavit. Alissa was treated at a hospital before police transferred him — using Talley's own handcuffs — to the Boulder County Jail. Police said they made sure to tell Alissa the handcuffs on his wrists were Talley's. Alissa has since been moved to a jail outside Boulder County due to safety concerns stemming from threats made against him that jail staff became aware of, Boulder County sheriff's spokeswoman Carrie Haverfield said in a statement Friday. Alissa did not enter a plea, which will come later in the judicial process, and is jailed without bail. Talley's funeral has been scheduled for Tuesday in the Boulder County city of Lafayette. Talley, who joined the police department in 2010, had seven children. Subscribe to our YouTube channel: https://bit.ly/2TwO8Gm Bloomberg Quicktake brings you live global news and original shows spanning business, technology, politics and culture. Make sense of the stories changing your business and your world. To watch complete coverage on Bloomberg Quicktake 24/7, visit http://www.bloomberg.com/qt/live, or watch on Apple TV, Roku, Samsung Smart TV, Fire TV and Android TV on the Bloomberg app. Have a story to tell? Fill out this survey for a chance to have it featured on Bloomberg Quicktake: https://cor.us/surveys/27AF30 Connect with us on… YouTube: https://www.youtube.com/user/Bloomberg Breaking News on YouTube: https://www.youtube.com/c/BloombergQuickTakeNews Twitter: https://twitter.com/quicktake Facebook: https://www.facebook.com/quicktake Instagram: https://www.instagram.com/quicktake