Who is David Scheiman from The Moor: A Mary Russell Novel and what is their importance?

David Scheiman is a con artist. Pretending to be Ketteridge's secretary, he is actually helping Ketteridge with the scam intended to create a gold rush on the moor. Scheiman is actually a Baskerville, whose ancestor was believed to have drowned on the moor. Thus, his main plan is to regain ownership of the Baskerville Hall.