I don't often say this this about you,.........but what you say makes a lot of logical sense on a strategic level here.
Unless the evidence was so enormous that she didn't even have the very tiniest sliver of a chance of ever winning or getting a lesser charge, or they were going after the death penalty if she didn't cop a plea I don't see the advantage of the plea deal considering she will be so old when she gets out it won't make that much practical difference from a life sentence.
Still somebody that bashes in another person's head in with a hammer and kills them should serve a long sentence.