In the year B.C.338 he poisoned Ochus, and placed upon the throne his youngest son, Arses, at the same time assassinating all the brothers of the new monarch.

It was evidently his aim to exercise the supreme power himself, as counsellor to a prince who owed his position to him, and who was moreover little more than a boy.

But Arses, though subservient for a year or two, began, as he grew older, to show that he had a will of his own, and was even heard to utter threats against his benefactor whereupon Bagoas, accustomed now to crime, secured himself by a fresh series of murders.

He caused Arses and his infant children to be assassinated, and selected one of his friends, Codomannus, the son of Arsanes, to fill the vacant throne.

About the same time (B.C.