DENVER (AP) — Lawyers are set to deliver closing arguments Friday in the trial of a mentally ill man who fatally shot 10 people at a Colorado supermarket in 2021.

Ahmad Alissa, who has schizophrenia, has pleaded not guilty by reason of insanity in the attack at the store in the college town of Boulder. His attorneys acknowledge he was the shooter but say he was legally insane at the time of the shooting.

Mental illness is not the same thing as insanity under the law. In Colorado, insanity is legally defined as having a mental disease so severe it is impossible for a person to tell the difference between right and wrong.

During two weeks of trial, the families of those killed saw graphic surveillance and police body camera video. Survivors testified about how they fled, helped others to safety and hid. An emergency room doctor crawled onto a shelf and hid among bags of chips. A pharmacist who took cover testified she heard Alissa say “This is fun” at least three times.

Several members of Alissa’s family, who immigrated to the United States from Syria, testified that starting a few years earlier he became withdrawn and spoke less. He later began acting paranoid and showed signs of hearing voices and his condition worsened after he got COVID-19 in late 2020, they said.

Alissa is charged with 10 counts of first-degree murder, multiple counts of attempted murder and other offenses, including having six high-capacity ammunition magazine devices banned in Colorado after previous mass shootings.

Alissa started shooting immediately after getting out of his car at the store on March 22, 2021, killing most of the victims in just over a minute. He killed a police officer who responded to the attack and then surrendered after another officer shot him in the leg.

Prosecutors said Alissa was equipped with an optic scope for his semi-automatic pistol, which resembled an AR-15 rifle, and steel-piercing bullets.

They accused him of trying to kill as many as possible, pursuing people who were running and trying to hide. That gave him an adrenaline rush and a sense of power, prosecutors argued, though they did not offer any motive for the attack.

State forensic psychologists who evaluated Alissa concluded he was sane during the shootings. The defense did not have to provide any evidence in the case and did not present any experts to say he was insane.

However, the defense pointed out that the psychologists did not have full confidence in their sanity finding. That was largely because Alissa did not provide them more information about what he was experiencing, even though it could have helped his case.

The experts also said they thought the voices he was hearing played some role in the attack and they did not believe it would have happened if Alissa were not mentally ill.