You put weight on the most peculiar things. The murder of Asmodean is one of the big mysteries in the series. Obviously he told Brandon exactly what happened so that the revelation would be accurate. It's illogical to think that an extensive note implies a complex scene.



The bandwagon isn't always wrong, and the rare opinion is often rare for a reason. The living Forsaken are the most reasonable suspects to kill Asmodean. Asmodean himself says that they would kill him on sight. Graendal, Sammael and Lanfear had the most opportunity. Lanfear was dead. Sammael was confused about Asmodean two books later.