I am also against the death penalty.
I would expect the criminal justice system would still continue investigating her murder even with him dead. If only to find possible accomplices and achieve a higher level of certainty that he was the only murderer. I don’t know how much of what they find will be shared with the families or public.
I understand you, and many others, feel strongly about him. There are very good reasons to write him off as garbage but even bad people make good decisions sometimes. Just as the reverse is true. I don’t have enough information on any of it to be able to say anymore than the whole thing is really sad and fucked up.
I’m having hard time with the concept of a selfish suicide. It’s counterintuitive to me that eliminating ones-self can be selfish.