The reports also noted that Devin Patrick Kelley was once caught trying to bring guns onto a military base and threatened superior officers there.
Kelley was also named as a suspect in a 2013 sexual assault in New Braunfels, about 35 miles from the scene of Sunday's church attack in Sutherland Springs.
The records that emerged on Tuesday add up to at least three missed opportunities that might have offered law enforcement a way to stop Kelley from having access to guns long before he slaughtered much of the congregation in the middle of a service.
Authorities said the death toll of 26 included the unborn baby of one of the women killed. Kelley died of a self-inflicted gunshot wound after he was chased by bystanders and crashed his car.
The Air Force confirmed on 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 on 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. Mr 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.
Associated Press via Press Association