The plot thickens. LOL. Bigger thinks that everyone is blind and that he wouldn't kill anyone. Is this the way he was raised (his environment). Probably. He thinks that he should get more money out of killing Mary. What a way to think!
Anyway, he just doesn't let things alone and will try the ransom route with the Dalton family. He is using Bessie to help him and is treating her real bad. It seems to me that Bigger is really in an ignorant state. He really thinkgs that he should have gotten more from Mary's death. How sad.