Accused Colorado gunman was often violent, paranoid, classmates say

March 24 (UPI) -- Ahmad al-Aliwi Alissa, the man accused of killing 10 people at a Boulder, Colo., grocery store, has been described by some people who knew him as often short-tempered, violent and paranoid.

Police say Alissa, 21, was the lone gunman in the mass shooting Monday at a King Soopers market.

According to investigators, Alissa walked into the supermarket wearing a tactical vest and carrying multiple weapons and opened fire. Among the 10 victims was an 11-year member of the Boulder police force.

Police named Alissa as the shooter on Tuesday, but have not given any details about why he may have targeted the store and why he wanted to kill anyone.

A few of Alissa's former schoolmates remember him as a sometimes angry young man.

"He was kind of scary to be around," Dayton Marvel, Alissa's teammate on the Arvada West High School wrestling team, told The Denver Post.

"His senior year ... he actually lost his match and quit the team and yelled out in the wrestling room that he was going to kill everybody," Marvel said. "We were just all kind of freaked out by it."

Another teammate told the Post Alissa could sometimes be paranoid and would express concern about being singled out because he was a Muslim.

"People chose not to mess with him because of his temper," former student Damien Cruz told CNN. "People chose not to really talk to him because of ... how he acted. ... He was very alone."

Alissa's family had emigrated from Syria to the United States. His older brother, Ali Aliwi Alissa, said treatment by classmates contributed to his antisocial behavior. Ahmad Aliwi Alissa became increasingly paranoid during his high school years and may have a mental illness.

"He always suspected someone was behind him, someone was chasing him," he told CNN. "We kept a close eye on him when he was in high school.

"He would say, 'Someone is chasing me, someone is investigating me.' And we're like, 'Come on man. There's nothing.' ... He was just closing into himself."

Ahmad Aliwi Alissa was wounded during Monday's attack. Officials said he was hospitalized for a non-life-threatening leg injury.

He faces 10 counts of first-degree murder.

Local and federal investigators are still looking into his background and trying to determine whether Monday's attack was a random act of violence or the people inside were specifically targeted.

Officials said Ahmad Aliwi Alissa bought one of the weapons just a few days before the attack, but noted that more than one weapon was found at the scene. A Colorado judge recently struck down a law that banned assault weapons in Boulder -- a ban that would have blocked the weapon police say Alissa bought before the shooting.

Alissa is scheduled to make his first court appearance on Thursday morning.