Encyclopedia Barsoomia Wiki
The information in this article comes from Dynamites, warlord of mars and is not written by Edgar Rice Burroughs.

Vem Drost was the Palace steward of the palace of Helium, he was paid by Zat Arras to help frame John Carter for the death of the caretaker with an amulet the therns provided for the task! Then murdered him and hid his body in a workers locker, possibly by Bantor Thren to reveal the therns and Zat Arrass' plot against Carter!