According to Plutarch, Hagnothemis was the authority upon which rested the belief that Antipater poisoned Alexander the Great, after he had heard King Antigonus speak of it. Plutarch gives no further biographical details for Hagnothemis, but he does state that, according to his account, Antipater undertook the assassination at Aristotle's instigation, and that it was Aristotle who procured the poison. Graham Phillips, in his investigation into Alexander's alleged murder, has speculated that it may have been Hagnothemis' testimony that so convinced Alexander's mother Olympias that her son had not died of natural causes.