The 1964 serial killer movie The Strangler is the masterpiece of director Burt Topper, who specialized in low-budget exploitation movies.
First, we see that lonely lab tech Otto Kroll (Victor Buono in an especially brilliant and eccentric performance) is twisted enough to murder random women and return to his lair to fondle his doll collection. Then we learn his motivation – he dutifully visits his hateful mother (Ellen Corby – later to play Grandma Walton) in her nursing room; she heaps abuse on him in every interaction. Pretty soon, even the audience wants to kill Mrs. Kroll, but Otto sneaks around taking out his hatred for his mom by strangling other women. Because Otto is outwardly genial to a fault, it takes a loooong time to fall under the suspicion of the cops. The character of Otto and Buono’s performance elevate The Strangler above its budget and launches it into the top rank of serial killer movies.
The Strangler, which plays occasionally on Turner Classic Movies, is only recently available to stream from Amazon.