Special Anthony Stewart, 24, of New York, was found dead Thursday night.
Around 11 p.m., police responded to Broadway near West 93rd Street, where they discovered Stewart with stab wounds to the torso.
NYPD Chief of Detectives Robert Boyce said Stewart and another man got into an argument and the suspect stabbed Stewart twice in his chest.
The suspect then walked north on Broadway to 96th street, said Boyce, adding that officers were trying to get surveillance video in the area.
Stewart was taken to Saint Luke's Hospital, where he was pronounced dead.
No arrests have been made. The investigation is ongoing.