All it would take is another judge deciding to overrule the first one.
That’s a remote possibility; another judge would have to overturn the actual plea-bargain Ridgway signed in order to get the life without parole sentence. The prosecutor was open to a death penalty trial, but Ridgway took the plea bargain instead.
From what I’ve read in follow-ups, Ridgway hasn’t fought his sentence in any way, shape or form.
Granted, any judge - or even a governor - can overturn a death penalty case, and look at the recent example of Richard Ramirez, the Night Stalker, who died of natural causes while on Death Row in San Quentin.
I guess the prosecutor in the Ridgway case had his reasons. In any event, the only place Ridgway will be hunting hookers anytime soon is in whatever twisted dreams he may have.