To be completely fair, what happened on December 4th is first degree murder. There was no self-defense component to legally justify the killing, so if Luigi is found to be the shooter, he is guilty of first degree murder. Those of us that like him just agree that he did the world a service and probably should be acquitted on that basis alone.
I don't really understand the "two counts of second degree murder" though. If I'm not mistaken, second degree murder is intentional killing caused by a sudden lapse in judgment, like murdering a man you found in bed with your wife. If he had a spiral notebook with details of premeditating the assassination and a written confession/"manifesto" as the authorities claim, then second degree murder shouldn't apply at all.