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

David Scheiman is a con artist. He passes himself off as Ketteridge's secretary, while actively assisting Ketteridge with the scam to create a gold rush on the moor. In reality, Scheiman is the son of a Baskerville, and his father was believed to have drowned on the moor. Scheiman goal is to regain ownership of Baskerville Hall and will do anything to accomplish his purpose.