Devin Kelley, the gunman in Sunday's massacre at a church in rural southeastern Texas, was convicted by court-martial of assaulting his first wife and stepson while serving in the U.S. Air Force in 2012, according to the Pentagon.
Authorities put the death toll at 26, including the unborn child of a pregnant woman who was killed. The attack ranks as the fifth-deadliest by a single gunman in U.S. history.
Investigators were still probing a conflict between Kelley and his in-laws that appeared to have set off his rampage, though the Federal Bureau of Investigation thus far has been unable to crack into the man's cell phone, officials said.
The Air Force said it had failed to transmit information about Kelley's conviction to the National Criminal Information Center system, a federal database used by gun dealers to check prospective buyers for criminal backgrounds.
The Republican chairman of the U.S. House Armed Services Committee called the failure to enter Kelley's record "appalling."
"I don't believe that the Air Force should be left to self-police after such tragic consequences," Representative Mac Thornberry of Texas said in a statement. "The failure to properly report domestic violence convictions may be a systemic issue."
The dead ranged in age from 18 months to 77 years. Twenty others were wounded, with 10 still in critical condition on Tuesday, officials said.
Kelley died of a self-inflicted gunshot wound in his getaway vehicle, where authorities found two handguns, said Freeman Martin, a spokesman for the state Department of Public Safety.
Kelley was also wounded by a resident of the community of about 400 people who heard the gunshot, grabbed his rifle and raced to the church, shooting the 26-year-old twice as he fled.
The massacre stirred an ongoing debate over gun ownership, which is protected by the Second Amendment of the U.S. Constitution. Guns are part of the fabric of life in rural areas.
U.S. President Donald Trump told reporters he believed stricter reviews of gun purchases would not have stopped Sunday's massacre.
"There would have been no difference," Trump said during a visit to South Korea. He added that stricter gun laws might have prevented the man who shot Kelley from acting as he did. "You would have had hundreds more dead."
Authorities said Kelley had been involved in a domestic dispute with the parents of his second wife, whom he married in 2014, and had sent threatening text messages to his mother-in-law before the shooting.
"We have some indication of what the conflict was between the family," Martin told a Tuesday press conference. "But there's still a lot of work to be done."
Although Kelley's in-laws occasionally attended services at First Baptist, they were not there Sunday.
Kelley's cell phone has been sent to the FBI's crime lab at Quantico, Virginia, where specialists have been unable to get into it to see if it holds details on the cause of his attack, said Christopher Combs, the FBI's special agent in charge in San Antonio.
"We are working very hard to get into the phone and that will continue until we find an answer," Combs told the Tuesday press conference.
AIR FORCE INQUIRY
The Air Force opened an inquiry into how it handled the former airman's criminal record, and the U.S. Defense Department has requested a review by its inspector general to ensure other cases have been reported correctly, Pentagon officials said.
Firearms experts said the case involving Kelley, who spent a year in military detention before his bad-conduct discharge from the Air Force in 2014, has exposed a previously unnoticed weak link in the system of background checks.
It is illegal under federal law to sell a gun to someone who has been convicted of a crime involving domestic violence against a spouse or child.
Federal databases did not contain any information that would have barred Kelley from legally buying the weapons police recovered, said the FBI's Combs.
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