BOULDER, Colo. - Ahmad Al Aliwi Alissa, 21, allegedly laughed and chuckled to himself as he went on a rampage through a King Soopers grocery store in Boulder, Colo., this week, killing 10 people.
"We could hear a man chuckling," Angelina Romero-Chavez, who was at the deli when the shooting started, told the Denver Post Saturday. "Gunshots were close. We believe it was him chuckling."
Police also noted the suspect's harrowing disposition, reporting over the radio, "This guy is laughing at us," according to the Denver Post.
Alissa has been charged with 10 counts of first-degree murder and made his first court appearance Thursday, when his lawyer asked for a mental health review.
"Our position is we cannot do anything until we are able to fully assess Mr. Alissa’s mental illness," Alissa's attorney, public defender Kathryn Herold, said in court.
Alissa was also charged with attempted murder, and Boulder County District Attorney Michael Dougherty said authorities plan to file more charges in the coming weeks.
Authorities have not yet released a motive and it is unclear why the grocery store was targeted.
"Like the rest of the community, we too want to know why — why that King Soopers, why Boulder, why Monday," Boulder Police Chief Maris Herold said at a news conference Monday. "It will be something haunting for all of us until we figure that out. Sometimes you just don’t figure these things out. But, I am hoping that we will."
The suspect acquired the Ruger AR-556 pistol, which resembles an AR-15 rifle, six days before the shooting at Eagles Nest Armory in the Denver suburb of Arvada, which is where he lived. He passed a background check conducted by the Colorado Bureau of Investigation.
He also had a 9 mm handgun, but police do not believe he used it in the shooting and it's unclear how he acquired it.
Officer Eric Talley, who was shot in the head and died, led a team of police into the store within 30 seconds of arriving at the scene.
"No other individuals were shot or killed after these brave officers engaged the suspect," Boulder police said Friday.
The other nine victims were Denny Stong, 20; Neven Stanisic, 23; Rikki Olds, 25; Tralona Bartkowiak, 49; Suzanne Fountain, 59; Teri Leiker, 51; Kevin Mahoney, 61; Lynn Murray, 62; and Jodi Waters, 65.
The Associated Press contributed to this report.
For more, go to Fox News.