The ABC15 Investigators have learned that the man who shot and killed four people in a Gilbert home on Wednesday was listed as a gang member by a Valley police agency.
In Mesa, J.T. Ready as a documented gang member because of his involvement with the National Socialist Movement, according to Sgt. Ryan Russell.
Russell is president of the Mesa Police Union and former leader of the city's gang squad.
There are roughly 3,300 documented gang members in Mesa. Russell told ABC15's that Ready was one of the few his officers knew by name.
"He was extremely confrontational and he was always armed," Russell said.
Police leaders told ABC15 that officers had made contact with Ready multiple times in the past.
Details about specific contacts were not immediately available.
However, in 2006, Ready was involved in a shooting on a Mesa street.
According to past media reports and court documents, Ready pursued an illegal immigrant in Mesa and confronted him.
Ready was dressed in tactical gear at the time and fired a shot at the man. He claimed the man, Efrain Martinez, attacked him and he acted in self-defense.
Martinez was arrested and charged with aggravated assault.
However, those charges were dropped, records show. An attorney for Martinez said there were questions surrounding the validity of Ready's account of what happened.
The Anti-Defamation League also told ABC15 that they had been monitoring Ready for at least the past decade.
He was on their radar because of his extreme views and periodic "patrols" on the border.
"We wouldn't even monitor J.T. Ready if we didn't feel there was a threat to public safety," said Bill Straus, ADL regional director.