Plutarch, Artaxerxes
Bernadotte Perrin, Ed.

29. Accordingly, Dareius put himself in the hands of Teribazus; and presently, when many were in the conspiracy, an eunuch made known to the king the plot and the manner of it, having accurate knowledge that the conspirators had resolved to enter the king's chamber by night and kill him in his bed. When Artaxerxes heard the eunuch's story, he thought it a grave matter to neglect the information and ignore so great a peril, and a graver still to believe it without any proof. [2] He therefore acted on this wise. He charged the eunuch to attend closely upon the conspirators; meanwhile he himself cut away the wall of his chamber behind the bed, put a doorway there, and covered the door with a hanging. Then, when the appointed hour was at hand and the eunuch told him the exact time, he kept his bed amid did not rise from it until he saw the faces of his assailants and recognised each man clearly. [3] But when he saw them advancing upon him with drawn swords, he quickly drew aside the hanging, retired into the inner chamber, closed the door with a slam, and raised a cry. The murderers accordingly, having been seen by the king, and having accomplished nothing, fled back through the door by which they had come, and told Teribazus and his friends to be off since their plot was known. [4] The rest, then, were dispersed and fled; but Teribazus slew many of the king's guards as they sought to arrest him, and at last was smitten by a spear at long range, and fell. Dareius, together with his children, was brought to the king, who consigned him to the royal judges for trial. The king was not present in person at the trial, but others brought in the indictment. However, the king ordered clerks to take down in writing the opinion of each judge and bring them all to him. [5] All the judges were of one opinion and condemned Dareius to death, whereupon the servants of the king seized him and led him away into a chamber near by, whither the executioner was summoned. The executioner came, with a sharp knife in his hand, wherewith the heads of condemned persons are cut off; but when he saw Dareius, he was confounded, and retired towards the door with averted gaze, declaring that he could not and would not take the life of a king. [6] But since the judges outside the door plied him with threats and commands, he turned back, arid with one hand clutching Dareius by the hair, dragged him to the ground, and cut off his head with the knife.

Some say, however, that the trial was held in the presence of the king, and that Dareius, when he was overwhelmed by the proofs, fell upon his face and begged and sued for mercy; [7] but Artaxerxes rose up in anger, drew his scimitar, and smote him till he had killed him; then, going forth into court, he made obeisance to the sun and said: ‘Depart in joy and peace, ye Persians, and say to all whom ye meet that those who contrived impious and unlawful things have been punished by great Oromasdes.’