Authorities in the hometown of the gunman who massacred worshippers at a Texas church are looking into whether they mishandled a sexual assault investigation of him four years ago.

Sheriff Mark Reynolds told San Antonio CBS affiliate KENS-TV that Comal County Sheriff's Office received a call on June 18, 2013, for a reported sex assault. The suspect is listed as Devin Patrick Kelley.

The report says deputies were sent around midnight on June 17, 2013, to the New Braunfels, Texas, home of Kelley's family.

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Reynolds told The Associated Press on Tuesday that it appears sheriff's deputies investigated the case for three months after being called to Kelley's home, but stopped investigating after they believed Kelley had left Texas and moved to Colorado. Reynolds said the case hasn't been touched since October 2013.

Reynolds took over the Sheriff's Office in January 2017.

Kelley opened fire Sunday at the First Baptist Church in Sutherland Springs, Texas, killing 26 people and wounding 20 others. Based on evidence at the scene, investigators believe Kelley died of a self-inflicted gunshot wound after he was chased by two men and crashed his car. It's still unclear why he opened fire on Sunday.

The Air Force confirmed Tuesday that Kelley had been treated in the facility after he was placed under pretrial confinement stemming from a court-martial on charges that he assaulted his then-wife and hit her child hard enough to fracture the boy's skull.

Involuntary commitment to a mental institution would have been grounds to deny him a weapon provided that records of his confinement were submitted to the federal database used to conduct background checks on people who try to purchase guns.

Kelley was also caught trying to bring guns onto Holloman Air Force Base in New Mexico when he was stationed there, according to an El Paso, Texas, police report released Tuesday.

While in the military, Kelley, who was 21 at the time, made death threats against superior officers, according to the June 2012 report, which also mentioned the military charges. He was eventually sentenced to 12 months of confinement for the assault.

The Air Force acknowledged Monday that it did not enter Kelley's criminal history into the federal database as required by military rules, another way he could have been denied a weapon.

Had Kelley been convicted of sexual assault, he would likely have been prevented from purchasing a gun because federal guidelines prohibit sales to anyone convicted of a felony punishable by more than one year in prison. The Comal County sheriff said he was reviewing whether his department mishandled the sexual assault investigation.

Authorities recovered a Ruger AR-556 rifle at the church and two handguns from the shooter's vehicle. All three weapons were purchased by Kelley, said Fred Milanowski, the agent in charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives in Houston.

The El Paso report notes that Kelley was committed to a mental health facility in Santa Teresa, New Mexico, but at some point escaped and was later found by police at a bus station in downtown El Paso in June 2012.

Deputies were called to Kelley's home in New Braunfels in June 2013 about the rape case and investigated for three months, Comal County Sheriff Mark Reynolds said. But it appeared that they stopped investigating after they believed Kelley left Texas and moved to Colorado. Reynolds said the case was then listed as inactive.

The sheriff said he was trying to determine how deputies came to believe Kelley had moved and why they did not continue to pursue the case, either in Colorado or after Kelley returned to the area later. Deputies were called to the same house in February 2014 to investigate a domestic violence report involving Kelley and Danielle Shields, his girlfriend at the time, whom he married two months later.

"The last information that we have is the suspect moved to Colorado and then the investigation seems to have tapered off," Reynolds said Tuesday. "That's what we're looking into."

The district attorney for Comal County said in an interview that she became aware of the sexual assault case Monday before the records were released to The Associated Press and other media.

"That case was never presented to our office," Jennifer Tharp said.

The records from Comal County also describe a burglary that Kelley's father, Michael, reported on his property the day after the sexual assault report. Michael Kelley told an officer that someone had taken a laptop computer and hard drive belonging to his son from a barn he had converted into an apartment for Devin Kelley. But Kelley said his son was unavailable to talk to police because he had been in a traffic accident that morning.

None of the documents explains whether there was a connection between the sexual assault report and the burglary report.