1. Hernandez kills Person A some time ago but isn't identified as the culprit at the time.
2. Hernandez kills Person B a few years later because Person B was a witness to the murder of Person A.
3. Hernandez is arrested for the murder of Person B. During the course of this investigation the police figure out that he also killed Person A.
4. He goes on trial for the murder of Person B. He's convicted and sentenced to a mandatory life sentence without parole.
5. In March 2017 he goes on trial for the murder of Person A. He's acquitted of this murder.
FWIW, I don’t think the dude offed himself.
Now that makes sense. Almost a Twilight Zone moment...”wait, I didn’t actually have to kill the guy I got popped for? Oh snap!”