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BOULDER, Colo. (KDVR) — Even if the man accused of killing 10 people at a Boulder King Soopers ends up using a mental illness defense, it’s no surprise a background check didn’t flag Ahmad Alissa as mentally ill when he bought his weapon six days before the mass shooting.

Defense attorneys for Alissa told the judge they need time to learn his history of possible mental illness. 

Alissa’s brother told the Daily Beast his brother was paranoid and “very anti-social” describing the shooting as “mental illness,” but the Arvada gun store that sold Alissa his Ruger AR-556 released a statement to FOX31 insisting Alissa passed a background check.

Eileen McCarron with Colorado Ceasefire isn’t surprised Alissa’s name didn’t show up on the National Instant Criminal Background Check System, better known as NICS.

“To be prohibited from buying a firearm on reasons of mental health is a high bar,” McCarron said.

Simply being diagnosed as mentally ill doesn’t put anyone on the NICS database maintained by the FBI. Instead a person has to be deemed mentally ill by a Colorado judge and then the State Court Administrator sends that information to the FBI.

Veterans can also be placed on the list if they are receiving disability payments for a mental illness and are under the care of a guardian. 

“You have to be adjudicated by a judge and perhaps institutionalized against your will so it’s not like going to a counselor because you’re depressed or having difficulties in your marriage,” McCarron said.

According to FBI stats obtained by the Problem Solvers, Colorado has 107,050 people on the NICS index who can’t legally buy a firearm for reasons of mental illness.

Nationwide, 56,830 people have been denied a gun since Nov. 30, 1998 because they were legally deemed mentally ill.

“There is no mental illness that is associated with a propensity to commit mass murder,” Vincent Atchity said, president and CEO of Mental Health Colorado.

Atchity said there needs to be more research done on who is likely to commit acts of violence but added, Alissa is someone who qualifies based on his misdemeanor conviction for attacking a high school classmate in the classroom.

“Was a pretty extreme assault,” Atchity noted, yet only felony assault convictions prevent someone from buying a gun unless the misdemeanor assault was related to domestic violence.   

Gun control advocates pushed for a measure in 2019 that would’ve added misdemeanor assault convictions as a reason to deny a gun purchase but the measure never made it out of a legislative committee.

Instead, Colorado lawmakers passed the state’s red flag bill.

That law might’ve helped prevent Alissa from purchasing or possessing a gun but it would’ve required Alissa’s family to file an Extreme Risk Protection Order, known as an ERPO.

“They maybe don’t know about the law or didn’t feel the situation was dire enough or they didn’t want to upset the son further or maybe they have fear of working with the courts or law enforcement,” McCarron said.