Bloodmoon (1997) on Netflix

Plot summary

Eddie Cunningham, the heavyweight boxing champion, is winding down a late workout at a New York City gym when a masked man in black appears, tells him he fights well but lacks the killer instinct, and points to the moon's faint red color. The man fights in boots edged with steel and finishes the bout with two steel fingers. Eddie's death is the fourth in a run of killings among the city's champions. Detective Chuck Baker catches the case, and Chief William Hutchins warns him to solve it or be transferred to Poughkeepsie. A man called Dutch, a former toughman champion, is attacked at his bar. Hutchins wants Chuck to meet Ken O'Hara, a serial killer specialist forced out of the unit after a near fatal case, and Ken, separated from his wife, is at the beach with his daughter.