I just saw this on TCM this morning. I agree that the other actors were quite wooden and some of the things the police overlooked (or the scriptwriter conveniently left out) were ridiculous, but Victor Buono was perfect as the killer and that is the reason to watch this film. They got much right about serial killers and their MO and "type" and Buono's ability to move from tenderness to arrogance and hatred creepiness and craziness - all with his face - was quite a thing to see. Just watch it for his portrayal. Ellen Corby as the harridan of a mother is quite fine too. The women who worked at the arcade were a bit dense, though I was glad to see the mother's nurse and the woman who worked with Buono in the lab were not. The movie is of its time, but Victor Buono is so good in this, it shouldn't be discounted.