The New York Ripper (1982)

When a serial killer starts targeting women in New York City, the police team up with a professor to discover the killers identity.
After a report that a woman was followed off a train and attacked by a man with two fingers, the police issue a APB for him.

The  report is heard on the radio by a prostitute spending the night a  two fingered man. She freaks out, runs into the hotel hallway to escape, and runs into the real killer at which point she will die die die.

And in an very odd twist (and you'll probably think I'm joking) the killer talks like a duck.  That's right, you heard me.  He makes a lot of phone calls and always sounds like Donald Duck, even when he's mad.  It's stupefying. The film is full of sleazy New York locations and disturbing kills, but then to completely throw you, there's this duck quacking on the phone.  It's bizarre.