Washington, Nov 10 (IANS): Devin Kelley, the gunman who killed 26 persons inside a church in Texas, had claimed that he bought animals for target practice, according to a former Air Force colleague.

Jessika Edwards, who worked with Kelley at Holloman Air Force Base in New Mexico from 2010 to 2012, said Kelley told her that he was "using the dogs as target practice".

The morbid admission came in Facebook messages starting in 2014, Edwards told CNN.

Though Edwards was not sure if Kelley was telling the truth, the odd behaviour was enough for her to stop communicating with him.

Kelley was accused in 2014 of punching a dog in Colorado. He initially pleaded guilty to animal cruelty, but the case was dismissed after he paid fines.

Edwards said Kelley also displayed a fascination with mass murders while he was enlisted in the Air Force.

"He would make jokes about wanting to kill somebody... And we would say, 'wait, that's not funny'."

The obsession was so pronounced, Edwards said, that when Kelley was disciplined for poor performance she told her bosses to "back off or he would shoot the place up".

"He was always getting into trouble... It was problem after problem," Edwards said.

A law enforcement source confirmed to CNN that FBI agents interviewed Edwards about her interactions with the gunman.

In 2012, Kelley was court-martialed and convicted for assaulting his wife and stepson.

Edwards said those domestic problems boiled over in the job and Kelley would come in depressed and unfocused.

After the shooting massacre on November 5, the Air Force has been criticised for failing to notify federal law enforcement officials of Kelley's conviction.

Kelley was dressed in black and wearing a bullet-proof vest when he attacked the church in Sutherland Springs, a quiet town some 45 km southeast of San Antonio.

The victims ranged from under two-years-old to 77.