Since he was a boy he has hated black men. A bitter hatred of black men that boiled in his mind and consumed him. Then last week, apparently, he decided to kill them.

This was the mind-set investigators say they gathered of James Harris Jackson, a morose and seemingly directionless 28-year-old white man who lived in Baltimore and had been having trouble getting rooted since leaving the Army. He had registered few obvious traces of who he was and what he stood for. Those who intersected with him found him to be a disagreeable and solitary figure who waved away contact with others.

By all accounts, Timothy Caughman, 66, was a benevolent man content with an unassuming life. He lived in a former single room occupancy residence that had been his longtime home. The son of a home health care aide and a pastor, he had worked in antipoverty programs in Queens. Religion and philosophy were constants in his conversations over unhurried meals of turkey bacon and grits at local diners. In recent years, he had caught the familiar New York infatuation with celebrities and delighted in collecting their autographs and pictures.

On St. Patrick’s Day, Mr. Jackson boarded a bus in Washington and rode it to New York. There were black men everywhere, and he told investigators he contemplated going elsewhere, but settled on New York because of the flood of media there. His goal was to draw the widest possible attention to his murderous plan.