A Milwaukee man who suspected his 13-year-old neighbor of breaking into his home and stealing weapons was convicted Wednesday of fatally shooting the boy as the teen’s mother looked on. Now, jurors will decide whether the 76-year-old defendant was mentally ill at the time.

A jury deliberated for about an hour before finding John Henry Spooner guilty of first-degree intentional homicide. Surveillance video from his own security cameras showed him confronting Darius Simmons in May 2012, pointing a gun at him from about 6 feet away and shooting him in the chest.

Spooner had entered two pleas to the homicide charge: not guilty and not guilty by reason of mental disease or defect. That set up the trial to be conducted in two phases: the first to determine whether he was guilty of the homicide, and if so, a second to determine whether he was mentally competent at the time.

With the first phase complete, the second began with testimony from a psychiatrist hired by the defense. Dr. Basil Jackson said his examination of Spooner revealed a man with anger issues who periodically dissociated from reality.

Spooner’s daughter once brought home a kitten that he didn’t want so he took it into the basement and killed it, Jackson said. Spooner also used to choke and beat his late wife, the doctor testified.

The violence shows Spooner occasionally loses the ability to control his anger — as during the moments that he shot Darius, Jackson said.

“There was an eruption, a loss of control. And at that moment he was not able — at that moment — to make a judgment,” Jackson said. “It’s like he was on autopilot.”

Spooner’s defense attorney, Franklyn Gimbel, never denied that his client shot Darius. Instead, he argued that Spooner didn’t mean for the gunshot to be fatal.

“This is not a case of whodunit,” Gimbel said. “It’s not a question of whether the behaviors of John Spooner caused the death of the young man — but what motivated it and what went on in his mind at the time is the crucial question.”