NEW YORK (AP) — A gunman who killed a former co-worker in cold blood in the shadow of the Empire State Building and then was shot dead by police after he turned his gun on them spent long hours in the quiet of Central Park, photographing hawks and marveling over nature's beauty.

His victim was a gregarious salesman, beloved by his nieces and nephews as the fun uncle who could talk with equal expertise about the New York Jets and the women's fashion accessories he sold.

Investigators on Saturday were trying to piece together what caused Jeffrey Johnson, a T-shirt designer, to ambush Steve Ercolino, an apparel company vice president, a day earlier outside the Manhattan offices of the company where they once were colleagues.