The Colorado gunman who killed 10 people at a Boulder, Colorado, supermarket in 2021 was found guilty of murder on Monday and now faces life in prison.

Ahmad Alissa, who was diagnosed with schizophrenia, was found guilty on Monday on several counts, including 10 counts of premeditated murder, 38 counts of attempted murder, one count of assault and six counts of illegal possession of large-capacity magazines.

Alissa, now 24, opened fire in a King Soopers grocery store in March 2021, killing nine customers and police officer Eric Talley, who arrived at the scene.

Alissa pleaded not guilty on the grounds of insanity. While defense attorneys did not dispute that Alissa shot and killed ten people, they argued that he was unable to distinguish between right and wrong at the time of the attack.

Prosecutors, however, painted a different picture, saying they had to prove that Alissa was sane at the time of the shooting. They argued that Alissa did not fire randomly, pointing out that he began shooting immediately after getting out of his car in the store’s parking lot. He killed most of the victims in just over a minute and surrendered after a police officer shot him in the leg.

Prosecutors added that Alissa demonstrated decision-making ability by chasing people who ran and tried to hide from him, while twice passing by a 91-year-old man who continued shopping without knowing about the shooting.

In addition, prosecutors said Alissa demonstrated that he took deliberate steps to make the attack as deadly as possible by being armed with steel-piercing bullets and illegal 30-round magazines.

Newsweek has emailed the Boulder District Attorney’s Office for comment.

Alissa’s mental state was a point of contention during the trial, as several members of his family, who immigrated to the United States from Syria, testified that he had become withdrawn and less vocal in the years before the shooting, and later became paranoid and showed signs of hearing voices.

According to his family, Alissa’s condition worsened after he contracted COVID-19 in late 2020. He was diagnosed with schizophrenia after the attack, and experts said behaviors described by relatives were consistent with the onset of the disease.

According to Colorado state law, insanity is a mental illness so severe that the person is unable to distinguish between right and wrong.

Despite his diagnosis of schizophrenia, state psychologists who examined Alissa concluded he was mentally healthy at the time of the shooting. Alissa reportedly heard “killing voices” before the attack. But experts said he was not delusional and his fear that he could be detained or killed by police showed he was aware of the consequences of his actions.

Meanwhile, the defense did not have to present any evidence in the case and could not present any experts who could prove Alissa’s insanity.

While prosecutors did not provide a motive for the attack, investigators found that Alissa had been scouting various public locations in Boulder, including bars and restaurants.

Sentencing is expected to take place later today. The victims’ families are expected to submit statements to the court. Colorado’s first-degree murder laws guarantee that Alissa will spend the rest of his life behind bars.

The courtroom on Monday was already full with families of the victims and police officers.

This article contains reporting from the Associated Press.