Ellery Queen
Ralph Bellamy
Nikki Porter
Margaret Lindsay
Rocky Taylor
Douglas Fowley
Zachary
Morgan Wallace
Amos
Byron Foulger
Valerie Norris
Katherine DeMille
Doctor's Assistant (uncredited)
Peter Bronte
Desk Sergeant (uncredited)
Jack Cheatham
Elevator Guard (uncredited)
Arthur Millett
Ambulance Driver (uncredited)
Frank O'Connor
Flynn (uncredited)
Lee Phelps
Rogers' Assistant (uncredited)
Jack Rice
Insp. Queen
Charley Grapewin
Elevator Passenger (uncredited) (unconfirmed)
Alan Ladd
Sgt. Velle
James Burke
Dr. James Rogers
Michael Whalen
Barbara Braun
Marsha Hunt
John Braun
Fred Niblo
Dr. Prouty
Charles Lane
Lydia Braun
Ann Shoemaker
Cornelia
Marion Martin
Director
Kurt Neumann
Story
Manfred Lee
Frederic Dannay
Screenplay
Eric Taylor
Director of Photography
James S. Brown Jr.