I don't know if Dexter Benner knew anything about Jean's disappearance but he comes across as extremely self-centered. I understand that he and Jean were not on good terms, but Christine had been living with her mother and grandmother until Jean disappeared. Not only was she in the middle of custody fights, but she had to cope with her mother vanishing, having her grandmother cut out of her life, and then he skips out of town with her and his second wife when a bench warrant was issued for his arrest. Didn't he think about how all this would affect his daughter? I'm not sure he cared, as long as he had her. I think he did turn her against her mother, when Jean wasn't there to defend herself. I think he resented the fact that Jean had won custody of Christine and didn't want Jean's mother to have any part of Christine's life or remind her of her mother.
As for Kirk Douglas, again, if he has any knowledge of this case I don't know, but I have heard the stories of him supposedly raping a teenage Natalie Wood; he was at one point engaged to Pier Angeli, who was 17 years younger than him, and broke things off with her because she wouldn't sleep with him. He also admitted in one of his books that he had issues with women and was quite violent and abusive in the bedroom. Also, I read somewhere that his statement to police (how strange was it that he contacted them before they had the chance to even seek him out) that he didn't know Jean personally angered her mother Florence because she recalled Douglas picking up her daughter at the house on more than one occasion. To be honest I've never liked him that much, he seems very arrogant.
The botched abortion thing seems the most likely, but the mob stuff seems a bit too coincidental to be entirely ruled out.
