The New York Ripper/Lo Squartatore Di New York (1982)

When the dog of an old man finds a decomposed hand in New York, the police identifies the victim as the model Ann-Lyne. Lt. Fred Williams is assigned to investigate the crime and is informed by Ann-Lyne's landlady that she had received a phone call from a man that spoke like a duck. While going to Staten Island, the bicycle rider Rosie is stabbed to death in the ferry by a man with duck-like voice. Lt. Williams teams-up with the psychologist Dr. Paul Davis to hunt down the serial-killer. Meanwhile other women are attacked by the murderer. When the beautiful Fay Majors survives the attack of the man, Lt. Williams and Dr. Davis have a lead to be followed but Dr. Davis questions whether the identified man is the killer since he believes the serial-killer has another profile.

IMDb: https://www.imdb.com/title/tt0084719