In "Death Lands a Hand," Robert Culp was not planning the murder. As he said when he was caught, it was an accident. To me, Dick Van Dyke, was a ruthless murderer. The way he killed his wife and then the man that helped him. I found that show very good.
I also feel that Mrs. Lyton ("Old Fashion Murder") was a "cold" bloodied murder. She seemed to have no affect after killing Mr. Schafer and her brother. There were some murderers that felt guilty - Johnny Cash ("Swan Song"), and Mr. Carsini ("Any Old Port in the Storm"). I don't know if you noticed but Robert Culp seemed to cry when he was caught in his three shows.