In the 1960s, Emile Griffith was a boxing star, known for his speed and punching power, with a regular presence at Madison Square Garden.

But in neighborhoods near the Garden, he let his other side show, one of flashy outfits and unapologetic swagger, where he frequented his favorite gay bars and clubs.

Mr. Griffith kept his two worlds separate. “He was living a double life, two lives, night and day,” said Willson Lee Henderson, a gay rights activist who said he met Mr. Griffith in early 1969 at the Stonewall Inn, the famous gay bar in Greenwich Village, several months before a police raid touched off the Stonewall Rebellion and the modern gay rights movement.