Pepe - actually we do know.
     
Jason Wallace, William Holmes, Rashan Brown, Marquez Pennington, Shelmar Johnson were responsible for the assault and - depending on which one you believe - either Wallace or Holmes was primarily responsible for his death.

Wallace (who is likely to be released from prison soon and who thanks to our former AG - now has immunity from prosecution) says Holmes was responsible.

Holmes (who will serve the rest of his life in prison regardless) - and various other acquaintances who testified - says Wallace was responsible.

Their written confessions - made independently at different times and at different places - are otherwise consistent with each other and with the other evidence.

The rush to prosecute someone, anyone for John Hartmann's death did two things:

    (1) It put four innocent men in jail.  

    (2) It allowed five thugs to get away with murder - and allowed those five thugs to go on and commit at least another six.