why wouldn't kelly just try to kill her mom?

Instead of all these huge obstacles they had to overcome, Kelly could have easily gotten her trust money if she had decided just to kill, or hire someone to kill her mom and frame somebody else. She didn't seem too fond of her mother anyhow. And I know she was in love with Sam and it was his idea, etc. But it just seemed she went through a lot of ridiculous things like having Suzie involved, going through the trial and ruining her reputation, being an accomplice in "murder", lying to the police, etc just to get money that was essentially, going to be hers anyway. Of course if they had just simply killed her mom to get the money this wouldn't be as much of an entertaining movie with all the double crossing and twists, but it was just something I was thinking about.