The Solitary Journey of Frank James, Who Wanted to ‘Watch People Die’

“He’s been on his own all his life, and I haven’t had that much contact with him,” she said. “He moves from city to city.”

One of the last of those cities was Milwaukee, where it was unclear what Mr. James did for work. He described himself as a driver, including for the delivery app Instacart. (Instacart did not reply to several requests for comment.)

He seems to have been more focused on his YouTube account, where the videos he posted frequently devolved into outbursts of homophobia, misogyny and offensive comments about Black people, Hispanic people and white people. Mr. James, who is Black, directed much his hatred toward Black people, whom he often blamed for the way they were treated in the United States.

He expressed admiration for Black trailblazers like Martin Luther King Jr. and President Barack Obama but unleashed vitriol on other Black people, including Daunte Wright, who was killed by a police officer in Minnesota last year, and other young Black men shot by the police. He blamed them for their own deaths, saying, “You play stupid games, you win a stupid prize,” and adding that they deserved to be shot.

Current and former neighbors in Wisconsin described him as gruff, standoffish and prone to losing his temper. Keilah Miller, who lived in an adjacent unit to Mr. James in Milwaukee, said he had blown up at her after she had left her key in her lock, yelling, “Don’t ever do that again!” She said he had few visitors.

A former neighbor, Mike Lopez, 38, said he never spoke to Mr. James but often saw him pushing a small cart with groceries or other possessions.

“I didn’t see him as no threat or nothing,” Mr. Lopez said before the arrest. “I mean, I don’t see him as capable as that. He can’t move like that, man. He wasn’t fast.” Mr. James’s sister also mentioned his physical difficulties, saying that he had a bad back and was not easily able to get up and down stairs.