What DID he do with her mother? (spoilers)
At the end, when Marie cuts off her father without a penny, she shouts, "What did you do with my mother."
Then Malmotte says, "That could not be helped." What did happen to her mother?
I think that it is strongly hinted that he murdered her . However , I havn't read the book, perhaps it elaborates there.
Gordon P. Clarkson
He probably poisoned her. He couldn't have remarried unless she was dead. So, he didn't just shuttle her off to a mental asylum.
I don't know everything. Neither does anyone else