Man shot neighbor he believed was a 'terrorist' in the head then went home to do his taxes, police say

Background: News footage of the apartment building in Milwaukee, Wis., where Angelo Nelson was shot on Feb. 2 (WITI). Inset (left): Dominic Nosacek (Milwaukee County Sheriff's Office). Inset (right): Angelo Nelson (@cbs58news/Instagram).

A Wisconsin man walked into a Department of Homeland Security office and told a security guard that he had shot his neighbor.

Dominic Nosacek, 31, is in custody at the Milwaukee County Jail after being charged with first-degree intentional homicide in connection with the fatal shooting of 50-year-old Angelo Nelson. According to a criminal complaint reviewed by Law&Crime, Nosacek reported the alleged crime himself on Monday morning when he showed up at an office building that houses a branch of the Department of Homeland Security (DHS).

A security guard told police that Nosacek entered the lobby at 11:25 a.m. and told him, "I just killed a militia, I shot him in the head."

The security guard called 911 after putting Nosacek through the lobby metal detector and making him sit in a chair. Nosacek told the guard that he left the rifle he used, an AK-47, at his apartment on N. Astor Street. According to the complaint, Nosacek told the guard that after he shot Nelson, he went back to his apartment and "did his taxes."

Police investigators said they spoke to a second security guard from the DHS building lobby who told them Nosacek said, "I just killed somebody" and called his victim a "terrorist."

Nelson's body was found in the hallway of the apartment. He died of a single gunshot wound to the head.

After investigators took Nosacek in for post-Miranda questioning, Nosacek was asked about the activity at his apartment building. He replied that his neighbors "bang around too much" and "harass" him. After informing detectives that he had a history of "psychosis" and "depression," Nosacek said that his neighbors were "militia men" who were "blackmailing" him.

Nosacek claimed that his neighbors did things to "provoke" him. When he saw Nelson standing in the hallway, he believed the other man was "waiting for him." As Nosacek left his own apartment, firearm in hand, he told police he shot Nelson so he "could not get to him."

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When asked if he intended to kill Nelson, Nosacek said, "Yeah, because they are militia." Nosacek said he did not see Nelson holding a weapon, and the two men did not have an argument.

Nosacek was charged with first-degree intentional homicide and bail jumping in connection with a previous criminal charge. After his first court appearance on Thursday, his bail was set at $251,000 cash. He remains in custody. His next court date has not been scheduled.

Nelson's best friend D'Juan Hill spoke to local Fox affiliate WITI to remember the man he knew since middle school, saying, "I want the world to know about Angelo Nelson."

Local CBS affiliate WDJT spoke to Nelson's mother, Patricia Donald, who told the station her son "was funny, he was a people person, he loved people."

Friends and family started a GoFundMe page to raise money for funeral costs.