Well, we don't really know what her lawyer is doing behind the scenes. I know some want to hear her speak, but the court of public opinion has already largely convicted her, and so her very well-respected lawyer may be playing it extremely close to the vest and telling her to do so as well. Honestly, even if she is innocent, her giving her side of things isn't going to help.
IMHO, silence has, so far, worked for Terri. There's been a lot of finger pointing and supposition, but no hard evidence. We're over a month out and she hasn't been arrested.