Ar, sulfur is definitely a clue. I see it something like this:
Sulfur could be a hint at the role of the deceased Lizard. Wesker, as we all understand, was one of the angels. So, it could have been like this:
Wesker came to collect the Lizard's soul. Sulfur is a hint at the Lizard's role (a hellish spawn). Hell sent either a Soul Eater or an Archon to kill him, while Wesker was most likely a seraphim. Wesker devoured the Lizard, who was a hellish spawn, after which an Archon or a Soul Eater came after Wesker (in this case, the spawn didn't have a Soul Eater).
I'll think about who to execute later...