From the interview of Mary's lawyer, (and I say this as a lawyer)it sounds more and more like a "diminished capacity" defense. He spoke of mental evaulations. May be PPD. Seems more and more like that is the case, or something similar. He described that she doesn't seem to comprehend the gravity of the situation...has the 1000 yard stare...and can't remember all that happened. She has mental problems it would seem.
At what point would they file for a change of venue. If he wants to show abuse or other negative behavior of the dead husband, they are going to have to make him out to be the villian. That may not go over well in the community they live d in.
Or practicing for her trial.