This is an interesting adaptation of the Edgar Allen Poe short story, THE MURDERS IN THE RUE MORGUE. Several women are brutally murdered and Inspector Bonnard is puzzled by this, as it seems the killer disappears into thin air. After all, how can he vanish out the window of a four story building? Then there's creepy Dr. Dr Marais (Karl Malden), who works at the local zoo. It's all too clear he's somehow responsible--but it's not him--it's a trained gorilla doing the slayings.
Although the gorilla costume is great, it was an Orangutang in the original story. I don't even think gorillas were "discovered" as a real animal until 1906--and this story takes place in the late 1800's.