John Henry Spooner, a 76-year-old Milwaukee Wisconsin man, was convicted on Wednesday of fatally shooting his 13-year-old neighbor whom he suspected had broken into his home and stole his weapons, the Associated Press reported. The trial now enters a second phase in which the defense will seek toprove that he was mentally ill at the time of the shooting.

Surveillance video from Spooner's security cameras showed that he confronted Darius Simmons in May 2012 and pointed a gun at him about 6 feet away before shooting him in the chest, the AP also reported.

His attorney Franklyn Gimbel said at the beginning of the trial that his client shot Darius but that he did not intend for the gunshot to be fatal.

"There was no mental investment in what he was doing," Gimbel said.

Darius' mother Patricia Larry testified that she chased her son until he collapsed in the street, as he died in her arms.

"I pulled his shirt up and I (saw) he had a bullet hole in his chest," Larry had testified. "He took one more breath and that's it."

When an officer arrived on the scene, Spooner reportedly said, "Yeah, I shot him."

During closing arguments, however, Gimbel insisted his client did not say that his admission of shooting Darius did not mean he wanted the victim to die.

"He didn't say, 'I killed the kid.' He didn't try to explain anything about the circumstances," Gimbel said. "That tells us this man was involved in an act where was not very much mental investment in what he was doing."