Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[244] Now it was Antipater who was the cause of all this; who when he knew what a mad and licentious way of acting his father was in, and had been a great while one of his counselors, he hurried him on, and then thought he should bring him to do somewhat to purpose, when every one that could oppose him was taken away. When therefore Andromachus and his friends were driven away, and had no discourse nor freedom with the king any longer, the king, in the first place, examined by torture all whom he thought to be faithful to Alexander, Whether they knew of any of his attempts against him; but these died without having any thing to say to that matter, which made the king more zealous [after discoveries], when he could not find out what evil proceedings he suspected them of. As for Antipater, he was very sagacious to raise a calumny against those that were really innocent, as if their denial was only their constancy and fidelity [to Alexander], and thereupon provoked Herod to discover by the torture of great numbers what attempts were still concealed. Now there was a certain person among the many that were tortured, who said that he knew that the young man had often said, that when he was commended as a tall man in his body, and a skillful marksman, and that in his other commendable exercises he exceeded all men, these qualifications given him by nature, though good in themselves, were not advantageous to him, because his father was grieved at them, and envied him for them; and that when he walked along with his father, he endeavored to depress and shorten himself, that he might not appear too tall; and that when he shot at any thing as he was hunting, when his father was by, he missed his mark on purpose, for he knew how ambitious his father was of being superior in such exercises. So when the man was tormented about this saying, and had ease given his body after it, he added, that he had his brother Aristobulus for his assistance, and contrived to lie in wait for their father, as they were hunting, and kill him; and when they had done so to fly to Rome, and desire to have the kingdom given them. There were also letters of the young man found, written to his brother, wherein he complained that his father did not act justly in giving Antipater a country, whose [yearly] revenues amounted to two hundred talents. Upon these confessions Herod presently thought he had somewhat to depend on, in his own opinion, as to his suspicion about his sons; so he took up Alexander and bound him: yet did he still continue to be uneasy, and was not quite satisfied of the truth of what he had heard; and when he came to recollect himself, he found that they had only made juvenile complaints and contentions, and that it was an incredible thing, that when his son should have slain him, he should openly go to Rome [to beg the kingdom]; so he was desirous to have some surer mark of his son's wickedness, and was very solicitous about it, that he might not appear to have condemned him to be put in prison too rashly; so he tortured the principal of Alexander's friends, and put not a few of them to death, without getting any of the things out of them which he suspected. And while Herod was very busy about this matter, and the palace was full of terror and trouble, one of the younger sort, when he was in the utmost agony, confessed that Alexander had sent to his friends at Rome, and desired that he might be quickly invited thither by Caesar, and that he could discover a plot against him; that Mithridates, the king of Parthia, was joined in friendship with his father against the Romans, and that he had a poisonous potion ready prepared at Askelori.