I haven't read into this particular situation, but it isn't uncommon for someone who has committed murder to plead insanity. My problem with such a general plead is that a majority of people who commit such acts are indeed insane, but that doesn't make them less of a threat to society. On the other hand, the specific circumstances leading to a murder are absolutely worth considering: we shouldn't just have a blind rule we follow in every situation. Each situation is individual. I just think pleading insanity is far too general a claim: that alone doesn't differentiate her from many other murderers.