BOULDER, Colo. (AP) — A man charged with killing 10 people at a Colorado supermarket last year is still incompetent to stand trial, a judge ruled Friday, keeping his prosecution on hold.

Court proceedings against Ahmad Al Aliwi Alissa, 23, have been paused since December, when a judge first found him to be mentally incompetent. The rulings mean he is unable to understand legal proceedings or work with his lawyers to defend himself.

Alissa remains at the state mental hospital, where he is receiving treatment, and was not in the Boulder courtroom Friday.

Alissa is accused of opening fire outside and inside a King Soopers store on March 2021 in the college town of Boulder. He killed customers, workers and a police officer who tried to stop the attack. Alissa surrendered after another officer shot and wounded him, according to authorities.

Investigators have not made public information about why they believe Alissa carried out the attack.

Alissa is charged with murder as well as multiple attempted murder counts for endangering the lives of 26 other people.

Alissa’s lawyers have not commented about the allegations. He has not been asked yet to enter a plea.

Reports about his mental health evaluations have not been made public. But court documents that addressed one of them last year said he was provisionally diagnosed with an unspecified mental health condition limiting his ability to “meaningfully converse with others.”

Competency is a different legal issue than a plea of not guilty by reason of insanity, which involves whether someone’s mental health prevented them from understanding right from wrong when a crime was committed.

Killed in the attack were Rikki Olds, Denny Stong, Neven Stanisic, Tralona Bartkowiak, Teri Leiker, Suzanne Fountain, Kevin Mahoney, Lynn Murray, Jody Waters and Eric Talley, who rushed into the store with an initial team of police officers.

Alissa lived in the nearby suburb of Arvada, where authorities say he passed a background check to legally buy the Ruger AR-556 pistol six days before authorities say he used it in the shooting.