Transcript for Air Force error allowed Texas church shooter to buy guns
going to discuss right now, that there is a demand for answers. They didn't tell the FBI about the gunman's history of domestic violence enabling him to purchase those weapons he used in the rampage. Our senior justice correspondent Pierre Thomas has more. Joins us from Washington. Good morning, piebre. Reporter: Robin, good morning. There's no soft way to put it, the killer should never have been able to buy the assault rifle used to massacre all those people. In April of 2016 Devin Kelley walked into this academy sports & outdoors store in San Antonio and brought awe Ruger assault rifle. A background check was done on the purchase. It came back clean and the sale of the weapon used to kill all those parishioners went forward. It should have never happened. There was no prohibitive information in the systems that we checked that say he could not have purchased that firearm. Reporter: These new documents obtained by ABC news military prosecutors outlined the details of Kelley's dark past. The court records show the former Arman pleaded guilty to repeatedly punching, kicking and choking his then wife. At another shocking charge, he's accused of striking his infant stepson on the head and body with a force likely to produce death or grievous bodily harm as part of the pleading the court-martial he dropped charges he pointed a loaded gun at his wife. It should have banned him from being able to buy the rifle but the air force last night admitted they never forwarded that information to the FBI which maintains the database used for those background checks. We have to get to the bottom of it. Yes, there are a lot of questions the air force has to answer. Reporter: This morning investigators searching for some of those answers in this tiny church and the staggering aftermath of Kelley's rampage. A substantial amount of evidence, physical evidence has been collected including hundreds of shell casings, more than 15 magazines, 30-round capacity magazines have been recovered. Reporter: And new insight into a possible motive. Again allegations of domestic violence. With police suggesting Kelley may have gone to the church to hunt his mother-in-law who allegedly received threatening text messages from the killer. There are many ways that he could have taken care. The mother-in-law without coming with 15 loaded magazines and an assault rifle to a church. I think he came here with a purpose and a mission. Reporter: While Kelley may have been after his mother-in-law, there's evidence that everyone in the house of worship was a target. Authorities have now studied video from inside that church. One official telling ABC news thegunman came to the church to, quote, kill everyone in that building, period. He was a mass killer of children, he's a horrible monster, end quote. Guys. And, Pierre, how does the military know there aren't others who haven't been flagged and could be out there right now? Reporter: Michael, we don't know if there are other cases like this falling through the cracks. The military is launching an investigation to make sure there are not more mistakes like this, all the services will be studied. Michael. Guys. Thank you, Pierre.
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