He didn’t get away with it in the legal sense. He was found guilty and sentenced to death, and what saved him was a general decision to stop carrying out the death penalty.
However, he still had ladies fawning over him even in recent years, and the media never stopped loving him, so I guess in that sense he succeeded.
But you have a point where you question whether it was all an act. It certainly looks like it when you observe his behavior. But if a person lies constantly for five decades while living in a 8x12 cell, at some point that person might start to believe his own bullshit. I would vote that he was crazy as a bat turd towards the end.