Transcript for Outrage grows over Texas massacre suspect's ability to buy weapons
Next here, to tin vest game. And so many red flags. The Pentagon also lunching an investigation tonight. The gunman was convicted of domestic violence in a military court. He escaped a mental health facili facility. And after all that, how was he still able to get those guns? Here's ABC's senior justice correspondent Pierre Thomas. Reporter: In April of 2016, Devin Kelley walk into this store in San Antonio and bought the Ruger assault rifle used to kill all those parishioners. An FBI background check came back clean. That should have never happened. I can tell you what is required and there was nothing in our databases that precluded him from purchasing a firearm. Reporter: Tonight, new details revealing Kelley was even more unstable and potentially dangerous than we knew, raising more questions about how he was able to buy multiple guns. Newly released police records show Kelley escaping from a New Mexico mental health facility in June of 2012. The police report noting Kelley suffered from "Mental disorders," had "Been caught sneaking firearms onto Holloman air force base" and was "Attempting to carry out death threats Kelley had made on this military chain of command." The escape came as Kelley was facing charges for punching and choking his wife and hitting his infant stepson "On the head and body with a force likely to produce death or grievous bodily harm." That domestic abuse coiction should have been shared by the air force from the FBI, blocking him from buying four guns. We've taken responsibility and we're going to find out what happened and fix it. Reporter: The Pentagon now reviewing what went wrong and whether other cases are also falling through the cracks. Tonight, as investigators dissect every detail of the killer's life, the FBI acknowledging they've yet to unlock Kelley's encrypted smartphone. I can assure you that we're working very hard to get into the phone. Reporter: That's the same problem that frustrated the FBI in the San Bernardino massacre for weeks. Pierre Thomas with us live again tonight. And Pierre, the question concerns many, if he got through the cracks, this suspect, how many others could there be? Reporter: David, some senators suspect the numbers could be high, and are pushing for specifics. There's worry that many agencies have not been pushing these domestic abuse convictions into the system for gun background checks. David? Pierre Thomas, our thanks to you.
This transcript has been automatically generated and may not be 100% accurate.