Right now it's free with adds on Tubi and Amazon, although I don't like watching movies with adds and if it was a Showtime movie then it probably didn't originally have them. But you can rent it on Amazon for 99 cents in SD or $2.99 HD.
>not only did that guy somehow get away with murdering two kids (bad screenwriting alert!)
He was found "not guilty by reason of insanity" and confined to mental hospital that he escaped from. Putting aside whether that verdict was realistic, he probably would have been in the mental hospital for life if he hadn't escaped.
I know very little about this issue and might be totally incorrect, but I think for the insanity defense to work it would have to be demonstrated that he was incapable of distinguishing right from wrong. I'm sure "right from wrong" here just means in conventional understanding, and not that it could be argued that he understood how the rest of society would percieve and react to the murders, but that he really thought they were a good thing.