Devin Patrick Kelley, a former US airman, was court-martialed for domestic violence while still on active duty in 2012 and was consequently barred from owning or buying firearms, presstv.ir reported.
However, the Air Force’s failure to enter his history into the national database allowed the disgraced serviceman to freely purchase a rifle last year and then use it in the attack in Sutherland Springs, Texas, killing 26 people.
Sessions said on Wednesday the shooting showed that not all the necessary information was being added to the National Instant Criminal Background Check System (NICS).
The attorney general said he was ordering the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) "to do a comprehensive review of the NICS and report back to me the steps we can take to ensure that those who are prohibited from purchasing firearms are prevented from doing so."
Kelley had been found guilty in 2012 of assaulting his first wife and a stepson. Federal law prohibits anyone from selling weapons to a person convicted of a crime involving domestic violence.
The Air Force has said it failed to inform the FBI about Kelley's criminal history as it was required. In addition to his court-martial, Kelley had also been investigated on a rape complaint, but no charges were filed against him.
Sessions said he was directing the FBI and ATF to check if the Pentagon and other government agencies were properly reporting information to the FBI's criminal database.
Law enforcement officials said Kelley’s rage towards his wife and her family might have been the real motives behind the attack.
Kelley, who killed himself during a getaway attempt after the shooting, had reportedly chosen the First Baptist Church in Sutherland Springs as his target because his most recent wife’s mother was a member there. She was not there at the time of the attack.