If he came out and confessed they could always find something. They wouldn't put him in jail for life and he'd never get a sentence anywhere near as harsh as murder 1.
It's tough to say what he would be charged on as different charges have different time limitations. For instance, time has probably run out on any domestic violence charges. The violation of civil rights is one I have heard of before. Also if they can show any of the wounds were inflicted post mortem he could get abuse of a corpse, etc.
Here's a case where a guy killed his fiance, was acquitted, and then when further evidence came out he confessed. They wound up putting him away for perjury a few times-
http://en.wikipedia.org/wiki/Mel_Ignatow