The emerging profile of shooting suspect Devin Patrick Kelley includes a history of mental instability and violence, police and military records show.

“It is clear this is a person who had violent tendencies,” Texas Governor Greg Abbott told CBS News.

“And someone who was a powder keg seemingly waiting to go off,” Governor Abbot added.

Kelley, 26, graduated from New Braunfels High School in 2009 and joined the U.S. Air Force.

While stationed at Holloman Air Force Base in New Mexico, he was court martialed in 2012.

He was charged with assault to his wife, Tessa Loge, and her young son. Published reports indicate Kelley fractured the boy’s skull.

Federal records confirm Kelley was sentenced to 12 months confinement and in 2014, he received a bad conduct discharge.

Kelley then moved back to Comal County Texas. In February 2014, the Comal County Sheriff’s Department responded to a domestic violence call that he was abusing his then-girlfriend Danielle Shields.

According to the sheriff’s department report, Shields sent a text message stating her arms were red and her boyfriend told her to pack a bag. A half hour later, the report indicates Shields advised the incident was a “misunderstanding” and “teenage drama.”

No charges were filed. Two months later, the couple was married in Comal County.

In August 2014, Devin Kelley was arrested in Colorado for misdemeanor cruelty to animals. A report from the El Paso County Sheriff’s Department states that witnesses observed Kelley punching his Husky several times. “The dog yelped repeatedly” according to the report.

The case was later dismissed.

Kelley once again moved back to Texas, staying in his parents’ New Braunfels home with his new wife Shields. Investigators said he sent threatening text messages to his in-laws, who were members of the church where the mass shooting occurred.

“You never think your neighbor is capable of something like that,” said neighbor Mark Morovitz.

“That kind of worries you, thinking we've been living next door to this guy,” he said.