(MILWAUKEE) -- The trial of George Zimmerman looms large over a court room more than 1,200 miles away in Milwaukee, where opening statements began Tuesday in a murder case in which a 76-year-old white man is accused of gunning down an unarmed black teenager.
John Henry Spooner, 76, is charged with first-degree intentional homicide in the shooting death of his neighbor, Darius Simmons, 13.
Spooner doesn't deny shooting the boy, but his lawyers have entered a plea of not guilty due to a mental illness that impaired his ability to know right from wrong, according to court papers.
Attorneys and the judge were concerned that the Florida case, which ended Saturday with Zimmerman's acquittal in the death of Trayvon Martin, would unduly influence the jury, which was selected on Monday.
Zimmerman admitted shooting Martin, but insisted he was acting in self-defense and was found not guilty.
"You understand the facts aren't the same. It's a whole different case," Judge Jeffrey Wagner told the Wisconsin jurors on Monday.
Spooner believed the boy had broken into his home and stolen guns from him, according to a criminal complaint filed by prosecutors.
Two days later, Spooner confronted Simmons on the sidewalk between their homes and accused him of taking the weapons. The boy denied stealing the guns, and Spooner shot him in the chest from just five feet away, according to court documents obtained by ABC News. The boy's mother saw the shooting.
On Monday, a 14-person jury was selected for the trial. At the end of the trial, two jurors will be randomly selected and removed from the panel before deliberations, leaving 12 members to decide the case.
Spooner never denied he shot the boy, according to a police officer who testified in court on Tuesday.
"Yeah I shot him," Spooner confessed at the scene, Milwaukee Police Officer Richard Martinez testified.
Spooner has pleaded not guilty and his attorneys have suggested they may argue his age and health have left him mentally diminished.
Calls to Spooner's defense attorney were not returned.
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