Yeah, he wouldn't admit to anything without a sped up death and guarantees that any sexual details wouldn't be released. That's if he had more to tell who knows.
The problem with Keyes is he told everyone he has no MO, he kills by different methods intentionally so LE don't suspect a serial killer, he never kills anyone he can be connected to and he kills any type of person male, female, young, old, whatever. This means that he automatically becomes a suspect in some peoples eyes in any unsolved murders in the cities/states he was known to be in at the time. Makes it impossible to narrow down the possibilities since he was everywhere. Whenever anyone attempts to tie him to a case it's circumstantial, honestly it'll simply be that he was in the City/State at the time of whatever murder as he'd popped up as a suspect on a few podcasts i listen to entirely based on that. I have to think LE have been going through unsolved murders in the areas he visited and trying his DNA against the ones with DNA samples.