Boulder, Colorado (CNN) — Ahmad Al Aliwi Alissa, who killed 10 people during a March 22, 2021, massacre at a King Soopers grocery store in Boulder, Colorado, is being sentenced Monday after a jury rejected his insanity claim and found him guilty of first-degree murder charges.

In finding Alissa guilty, the jury – which deliberated for a little more than five and a half hours over two days – rejected his insanity claim.

In addition to the 10 counts of murder, Alissa, 25, was convicted of 45 other felony counts, including attempted murder, assault and using a prohibited large-capacity magazine during the commission of a crime.

Alissa’s attorneys didn’t deny he committed the shooting. To determine whether he was legally insane at the time of the shooting, jurors needed to weigh whether they believed he was able to form intent or distinguish right from wrong.

Speaking ahead of the sentencing Monday afternoon, Nikolina Stanisic, whose 23-year-old brother, Neven, was killed in the shooting, described her sibling as “a caring, kind and selfless person.”

He was their parents’ “first joy, their first happiness, and their first sadness and heartbreak,” she said.

“Our life without Neven is not a complete whole life,” she went on. “There’s someone who is always missing.”

Over the past few weeks, jurors at Boulder County District Court heard 10 days of testimony, during which the prosecution argued that despite being diagnosed with schizophrenia after the shooting, Alissa was legally sane when he carried out the attack.

The shooter was found incompetent to stand trial in 2021 but then deemed competent in 2023 after undergoing treatment in a state hospital.

“The evidence in this case is straightforward. What happened on March 22 of 2021 is not a mystery; it was on video,” Assistant District Attorney Ken Kupfner said in his closing argument, before ticking through every felony count Alissa is facing and pointing to the actions that prosecutors say prove beyond a reasonable doubt he acted “after deliberation, and with intent.”

Alissa is “not somebody who is insane. … Somebody who thinks a mass shooting is fun, they’re sick. We agree he’s mentally ill. He has schizophrenia, but he’s not insane,” Kupfner said.

Alissa’s defense attorney Kathryn Herold told the jury in her closing argument that “this tragedy was borne out of disease, not choice.”

“Mr. Alissa committed these crimes because he was psychotic and delusional on March 22 of 2021,” Herold said. “We also know that but for the psychosis he was suffering, this tragedy would never have happened.”

‘He’s given us a life sentence, robbing us of family’

Many of the victims’ family members appeared in court and became emotional and tearful as the verdict was read. Ahead of Alissa’s sentencing, several family members shared wrenching tributes to their loved ones and described the pain they have suffered since the shooting.

“The images of my son’s brains and blood splattered on a grocery store floor will be with me forever,” said Shay Talley. His son, Eric Talley, a Boulder police officer, was gunned down in the shooting. “But I still choose to forgive. Eric would want us to forgive. He was a very forgiving person.”

“We want the shooter to know this murder has changed us,” said Margie Whittington, whose daughter, Teri Leiker, was killed. “We will never be the same. We will never get over losing her, especially in such a horrible way.”

“Life after Teri has been devastating, but we are not devastated,” she went on.

Olivia MacKenzie, who lost her mother, Lynn Murray, called for a life sentence for Alissa.

“He’s given us a life sentence, robbing us of family,” she said. “Why should he get any less?”

“I felt like, and do still feel like, the luckiest daughter on Earth to have been so lucky to have been her kid,” she said of her mother.

Erika Mahoney, whose father, Kevin Mahoney, was killed, said she hoped for an apology from Alissa’s side.

“If we’ve never been denying he did it, then where’s an apology?” she asked. “An iota of remorse from them or his family would have gone a long way. The door is still open.”

Addressing Alissa directly, she said, “I’m sorry for your suffering – past, present and future. As I said earlier, I wish you would have gotten more love.”

An older brother of Alissa, who didn’t give his name, spoke to CNN affiliate KUSA after the verdict was read. He described his brother as “calm” if at times “antisocial” and said the family didn’t know he had schizophrenia. They “would never in a lifetime think that he was, you know, able to do something like this.”

“From the bottom of my heart, we are so sorry, as his family, we are so sorry,” he said. “I wish we can rewind time, but there is no way that we can rewind time.”

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