SUTHERLAND SPRINGS, Tex. \u2014 The gunman behind the worst mass shooting<\/a> in Texas history escaped from a psychiatric hospital while he was in the Air Force, and was caught a few miles away by the local police, who were told that he had made death threats against his superiors and tried to smuggle weapons onto his base, a 2012 police report showed.<\/p>\n That episode, which came to light on Tuesday, was another in a series of red flags about the threat the gunman, Devin P. Kelley, posed to those around him. But none of the warnings stopped Mr. Kelley from legally purchasing several firearms, including the rifle he used to kill 26 people at the First Baptist Church of Sutherland Springs on Sunday.<\/p>\n According to an El Paso Police Department report from June 2012, officers took Mr. Kelley, then 21, into custody at a bus station in downtown El Paso, where he apparently planned to flee on a bus after escaping from Peak Behavioral Health Services, a hospital a few miles away in Santa Teresa, N.M. He had gone to Peak Behavioral, whose services include a program for military personnel<\/a>, after being charged in a military court with assaulting his wife<\/a> and baby stepson, charges he later pleaded guilty to.<\/p>\n The report filed by the El Paso officers says that the person who reported Mr. Kelley missing from the hospital advised them that he \u201csuffered from mental disorders,\u201d and that he \u201cwas attempting to carry out death threats\u201d against \u201chis military chain of command.\u201d The man \u201cwas a danger to himself and others as he had already been caught sneaking firearms onto Holloman Air Force Base,\u201d it added.<\/p>\n Federal law prohibits gun possession by anyone who \u201chas been committed to any mental institution,\u201d which occurs after a legal process, but it was unclear if that had happened to Mr. Kelley. The Air Force said that Mr. Kelley had been taken to the hospital while he was jailed on the assault charges, and that it was still reviewing records of his case.<\/p>\n But Mr. Kelley had clearly been troubled for years. His public school records released on Tuesday showed he had been suspended at least seven times, and a classmate said he had complained about medication he was taking.<\/p>\n Months after his escape from the psychiatric hospital, Mr. Kelley pleaded guilty in a military court to repeated assaults on his first wife and her son, a toddler, including one that left the boy with a fractured skull. He was sentenced to a year in confinement.<\/p>\n That conviction should have barred him from buying firearms, but instead, he was able to buy several, passing a background check each time. Federal law prohibits gun purchases by people who have been convicted of domestic violence, but the Air Force admitted<\/a> on Monday that it had failed to report Mr. Kelley\u2019s case to the federal databases used for such background checks. The Air Force said it was investigating whether other convictions had also been left unreported.<\/p>\n There were other signs of trouble for Mr. Kelley, who received a \u201cbad conduct\u201d discharge from the Air Force after finishing his sentence. In 2013, he was investigated by the Comal County Sheriff\u2019s Office on a complaint of rape and sexual assault in New Braunfels, Tex., his hometown, but no charges were filed. A statement from the sheriff\u2019s office said on Tuesday that the investigation had \u201cstalled sometime in October 2013 for reasons yet to be determined.\u201d<\/p>\n Mr. Kelley then moved to a recreational vehicle park in Colorado Springs, where four witnesses told the police that they had seen Mr. Kelley chase down his white-and-brown Siberian husky and punch the dog four or five times, yelling at it, before dragging it into his camper, according to a report from the sheriff\u2019s office in El Paso County, Colo. Mr. Kelley was charged with animal cruelty, pleaded guilty and received a deferred sentence, records show.<\/p>\n Brent Moody, a neighbor who called the police, said in an interview that he and his wife moved out sooner than they would have liked because they were scared of Mr. Kelley. \u201cIn his eyes, he looked like there was intense anger,\u201d Mr. Moody said. \u201cSomething didn\u2019t seem right with him.\u201d<\/p>\n Last Sunday morning, Mr. Kelley took a Ruger AR-556 assault rifle to the First Baptist Church and opened fire, killing 26 people and wounding at least 20 others. After a shootout outside the church with a bystander, in which he was hit twice, Mr. Kelley raced away in his car, chased by the bystander and another man, and soon crashed. He was found dead, having shot himself in the head.<\/p>\n Officials have said that the massacre may have stemmed from acrimony between Mr. Kelley and the family of his estranged second wife. His mother-in-law, who attended the church, was not there on Sunday, but his wife\u2019s grandmother was among those killed.<\/p>\n But as they try to delve deeper into what might have motivated the rampage, investigators said, they have hit a roadblock: They have not been able to unlock the killer\u2019s cellphone, reviving an issue that received national attention after another mass shooting two years ago.<\/p>\n \u201cUnfortunately, at this point in time, we are unable to get into that phone,\u201d Christopher H. Combs, the special agent in charge of the F.B.I.\u2019s San Antonio office, said. He refused to name the brand of the phone, saying that it would encourage other criminals to get the same kind.<\/p>\n After 14 people were shot to death<\/a> in a conference room in San Bernardino, Calif., the F.B.I. was unable to unlock an iPhone belonging to one of the attackers. The bureau went to court to try to force Apple to build a software \u201cback door\u201d allowing law enforcement agencies to get into phones, but the company refused.<\/p>\n