Artabanus was according to Aristotle responsible for the death of Crown Prince Darius. He then became afraid that Xerxes would seek revenge and proceeded to assassinate the King. On the other hand Junianus Justinus reported that Artabanus had personal ambitions for the throne. He first secretly murdered Xerxes and then accused Darius of patricide, resulting in his execution. The order of events remains uncertain but Xerxes and Darius certainly left the throne vacant.
Artabanus' course of action is also uncertain. Some accounts have him usurping the throne for himself. Others consider him to have named young Artaxerxes I as King and to have acted as Regent and power behind the throne. This state of affairs would not last more than a few months. Artabanus was reportedly personally slain by the sword-wielding Artaxerxes I either in battle or by surprise. Artabanus is occasionally listed among the Kings of the Achaemenid dynasty though he was not related to them.