SUTHERLAND SPRINGS, Tex. — The gunman behind the worst mass shooting 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.
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.
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, after being charged in a military court with assaulting his wife and baby stepson, charges he later pleaded guilty to.
The report filed by the El Paso officers says that the person who reported Mr. Kelley missing from the hospital advised them that he “suffered from mental disorders,” and that he “was attempting to carry out death threats” against “his military chain of command.” The man “was a danger to himself and others as he had already been caught sneaking firearms onto Holloman Air Force Base,” it added.
Federal law prohibits gun possession by anyone who “has been committed to any mental institution,” 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.
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.
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.
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 on Monday that it had failed to report Mr. Kelley’s 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.
There were other signs of trouble for Mr. Kelley, who received a “bad conduct” discharge from the Air Force after finishing his sentence. In 2013, he was investigated by the Comal County Sheriff’s 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’s office said on Tuesday that the investigation had “stalled sometime in October 2013 for reasons yet to be determined.”
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’s office in El Paso County, Colo. Mr. Kelley was charged with animal cruelty, pleaded guilty and received a deferred sentence, records show.
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. “In his eyes, he looked like there was intense anger,” Mr. Moody said. “Something didn’t seem right with him.”
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.
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’s grandmother was among those killed.
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’s cellphone, reviving an issue that received national attention after another mass shooting two years ago.
“Unfortunately, at this point in time, we are unable to get into that phone,” Christopher H. Combs, the special agent in charge of the F.B.I.’s 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.
After 14 people were shot to death 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 “back door” allowing law enforcement agencies to get into phones, but the company refused.
Before the issue could come to a head, the F.B.I. hired hackers who were able to unlock the phone.
On Capitol Hill on Tuesday, the debate over the Texas shooting fell predictably along party lines, with Democrats calling for more gun safety legislation and Republicans resisting. But there was one notable exception: The No. 2 Republican in the Senate, John Cornyn of Texas, said he had begun work on a measure that would improve reporting to the background check system used for gun purchases.
“Obviously if things like this can happen in spite of the law then we need to look at that and try to fix it the best we can,” Mr. Cornyn told reporters, adding, “This is one of those areas of consensus on a very contentious topic.”
But on the other side of the Capitol, House Speaker Paul Ryan said no new legislation was needed. “The laws we have right now on the books say a person like this should not have gotten a gun,” Mr. Ryan said. “So this speaks to making sure that we actually enforce our laws that we have on the books.”
Vice President Mike Pence and his wife, Karen, were scheduled to visit Sutherland Springs on Wednesday. President Trump, on his Asian trip Tuesday, said that stricter gun laws would not have prevented the shooting. In fact, he said, they could have driven the death toll into the hundreds, since the gunman had been shot by an armed bystander.
Gun-control advocates said Mr. Kelley should not have had that kind of firepower in the first place. Senator Dianne Feinstein, a California Democrat, said that she had been monitoring mass shootings since the 1966 massacre at the University of Texas — and that she had never felt more dispirited.
“Never did I believe there would be children killed, babies killed, 6-year-olds killed,” Ms. Feinstein said.
While no one who knew Mr. Kelley said they believed was capable of such an atrocity, his troubles were not hidden.
Public school administrators in New Braunfels suspended him at least seven times. Mr. Kelley’s disciplinary record showed a variety of offenses, including insubordination, profanity, dishonesty and drugs.
His high school health records said that he had been diagnosed with attention deficit hyperactivity disorder and had a vision disorder. His academic record was lackluster, with a grade-point average of 2.32. He finished 260th in his class of 393.
Reid Mosis, a classmate from the sixth through ninth grades, said Mr. Kelley often griped about his parents and how they were insistent that he undergo drug treatments, apparently for emotional issues.
“He complained a lot about his parents and the medications he was taking,” he recalled. “He said that his parents were trying to fix him. But he didn’t say what for, specifically.”
Mr. Mosis noted that Mr. Kelley “got irritated easily and always seemed angry.”
Even the pastor of First Baptist, Frank Pomeroy, sensed trouble, according to Sheriff Joe Tackitt of Wilson County, which includes Sutherland Springs.
Mr. Pomeroy told the sheriff that Mr. Kelley had attended the church in the past, the sheriff said on Tuesday. Mr. Pomeroy “didn’t like the guy,” the sheriff said, but did not feel he could turn Mr. Kelley away.
Mr. Pomeroy was not at church on Sunday, but his 14-year-old daughter, Annabelle, was among those killed. The dead included at least a dozen children, the youngest 18 months old.
Joaquín Ramírez, a parishioner who was standing near Annabelle, recalled how Mr. Kelley, dressed in all black and wearing a skull-face mask, had methodically fired as he walked among the pews.
“You’re gonna die!” Mr. Kelley yelled out, followed by an expletive, Mr. Ramírez said. Mr. Ramírez, whose girlfriend was shot and survived, was still shivering on Tuesday as he recalled the horror, and how Mr. Kelley, it seemed, “aimed specifically at the little children.”