Mortis is the one who attempted to kill Gus, Sirius is just an innocent scapegoat...?
This theory may seem crazy, but please read on
Since no one would die in Starr Park, Mortis wants to create the first corpse. Judging from Gus's grave, Gus might have been his target, he attempted to kill him for his career
As for why Sirius became a scapegoat, I don't think it was Mortis who directly shifted the blame to him (There is currently no indication that they know each other) I think the most likely explanation is that, over time, related rumors gradually evolved into the story that Sirius killed Gus (he seemed to have stolen his shadow increased the credibility of the story), for this reason, no one suspected Mortis
What are your thoughts on this?