A judge ruled Friday that a man charged with killing 10 people at a Colorado supermarket last year is still mentally incompetent to stand trial, further delaying court proceedings in the case.

The prosecution of Ahmad Al Aliwi Alissa, 22, has been on hold since December, when Judge Ingrid Bakke ruled that he was mentally incompetent — unable to understand legal proceedings and work with his lawyers to defend himself.

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The ruling came nearly a month after Boulder, the home of the University of Colorado, marked the first anniversary of the attack that killed workers, customers and a police officer who rushed inside the store. Alissa was not in court for Friday’s hearing.

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Ahmad Al Aliwi Alissa, the man accused of killing multiple people at a Colorado supermarket in March 2021, is led into a courtroom for a hearing, Sept. 7, 2021, in Boulder, Colo. A judge ruled Friday, April 15, 2022, that Alissa, charged with killing 10 people at a Colorado supermarket last year is still mentally incompetent to stand trial, further delaying court proceedings in the case. (AP Photo/David Zalubowski, Pool, File)

Few details have been released about Alissa’s condition. Reports on his evaluations are not available to the public, but a court filing discussing one of the evaluations last year said he had been provisionally diagnosed with an unspecified mental health condition that limits his ability to "meaningfully converse with others."

In December, one of Alissa’s attorneys, Kathryn Herold, said her client has a "serious" mental illness but did not elaborate. At the time, District Attorney Michael Dougherty said Alissa had "deteriorated" over the previous months while being held in jail.

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Investigators have not released any information about why they believe Alissa launched the attack or why he may have targeted the supermarket. He lived in the neighboring suburb of Arvada, where authorities say he passed a background check to legally buy the Ruger AR-556 pistol he allegedly used six days before the shooting.

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 at the time a crime was committed.

The judge set a July 21 hearing to again evaluate Alissa’s competency to stand trial.

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Ahmad Al Aliwi Alissa listens during a hearing in Boulder, Colo., Sept. 7, 2021. A judge ruled Friday, April 15, 2022, that Alissa, charged with killing 10 people at a Colorado supermarket last year is still mentally incompetent to stand trial, further delaying court proceedings in the case. (AP Photo/David Zalubowski, Pool, File)

The March 22, 2021, attack at a King Soopers grocery shocked a state that has seen its share of mass shootings, including the 1999 Columbine High School massacre and the 2012 Aurora movie theater shooting.

Boulder police Officer Eric Talley, a 51-year-old father of seven, was shot and killed while rushing into the store with an initial team of police officers. The nine others killed inside and outside the supermarket were Denny Stong, Neven Stanisic, Rikki Olds, Tralona Bartkowiak, Teri Leiker, Suzanne Fountain, Kevin Mahoney, Lynn Murray and Jody Waters.

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Stong, Olds and Leiker worked at the supermarket.

The remodeled King Soopers reopened in February, with about half of those who worked there at the time of the shooting choosing to return.