Who did he kill anyhow?
From the wiki link...
On August 22, 2013, Hernandez was indicted by a grand jury for the June 2013 murder of Lloyd, who was a semi-professional football player.[7] He was found guilty of first-degree murder in the Lloyd case, and sentenced to serve life in prison without the possibility of parole at the Souza-Baranowski Correctional Center.[8] He was also indicted for the 2012 double homicide of Daniel de Abreu and Safiro Furtado,[6] but was found not guilty.[9] On April 19, 2017, Hernandez was found dead in his prison cell, having apparently committed suicide.[10][11][12]
It is possible that Hernandez, because of his death, may be considered by law to be innocent of the Lloyd murder. Under a legal doctrine in use in Massachusetts called abatement ab initio, if someone dies after a conviction but before the completion of their appeal, the person’s legal records in that matter may be wiped clean with the conviction vacated.[13]
https://en.m.wikipedia.org/wiki/Aaron_Hernandez