Gunman who killed 10 in Colorado convicted of murder

Rejecting an insanity defense, a Colorado jury has convicted a man diagnosed with the severe mental disorder schizophrenia of first-degree murder in a 2021 mass shooting at a grocery store in the city of Boulder that killed ten people including a police officer.

Ahmad Al Aliwi Alissa, 25, had pleaded not guilty by reason of insanity.

The jury instead found the Syria-born man guilty in Boulder District Court on ten counts of first-degree murder.

In Colorado, a first-degree murder conviction carries a mandatory sentence of life in prison without the possibility of parole.

Had Alissa been found not guilty by reason of insanity, he would have been sent to the state psychiatric hospital, with any release from that facility requiring a judge's approval.

It was never in dispute that Alissa carried out the rampage.

The case focused on his mental state at the time of the shootings.

Under Colorado law, a person must be found to be unable to distinguish between right and wrong for an insanity defense to prevail.

Authorities said Alissa was armed with a legally purchased Ruger AR-556 pistol, which resembles an AR-15 semiautomatic rifle, when he entered the King Soopers grocery store in Boulder, about 50km northwest of Denver, on 22 March 2021.

Alissa shot dead two people in the parking lot before entering the store and killing eight others, including a police officer who responded to the shooting.

"He is methodical and he is brutal," District Attorney Michael Dougherty told jurors in closing arguments.

The psychologists and psychiatrists who testified during the trial agreed that Alissa was diagnosed as a schizophrenic who was profoundly mentally ill.

But that diagnosis alone does not render a person legally insane.

"This tragedy was born out of disease not choice," defense attorney Kathryn Herold told the jury.

Eyewitnesses described Alissa as focused as he opened fire, shooting dead at least two victims at point-blank range after wounding them in the opening salvo.

Sarah Chen, a pharmacist working that day, testified during the trial that she heard Alissa shriek with delight as he fired his weapon as she and other workers crouched behind a counter.

"He said, 'This is fun, this is so much fun,'" Ms Chen testified.

Alissa was born in Syria and his family emigrated to the United States when he was a small child and settled in a Denver suburb.

His parents and some of his siblings testified that in high school Alissa started becoming withdrawn, acting in a paranoid manner and talking to himself.

"It's shameful in our culture if we say our son is crazy," his father, Moustafa Alissa, testified. "We were thinking he was probably possessed by spirits."

Alissa did not testify in his own defense.

The mental health workers who interacted with the defendant since his arrest testified that he never articulated a clear motive for the massacre.