I think it is pretty common for these sociopath types to never, ever admit guilt, no matter how strong the evidence against them. It is like when LE confronted Scott Peterson with photos of him and Amber Frey together at a party. His response was "Are you saying that's me?"
It's the old "prisons are full of innocent people" thingy.
As far as the defense lawyers, I've often wondered about how they advise clients about taking a plea right before trial is to begin. Would their income not be much higher for participating in a trial? Not saying that the money factor would influence how an attorney advised a client, of course..... I'm sure no lawyer would ever do that.
I once had a (dumb) neighbor who did something that turned out to be a crime. (Not violence, it was more "white collar".) He was arrested and charged with every little thing related to the event. He got a lawyer who was immediately urging him to take a plea deal. I advised him to get a different attorney, which he did not do.
Anyway, he kept refusing the lawyers advice to take a plea. Finally, just when it was about to go to trial, the Prosecutors majorly changed the plea deal offer, dropping all charges except one, which they would lower to a lesser charge, etc. A "really sweet deal" so to speak. So he took that deal and was even able to plead "nolo contendere" (sp?) which technically is not a guilty plea.
If he had followed the advice of his attorney and taken the first deal offered, his outcome would have been quite different.