Περιστάσης δὲ τῆς πάσης εἰς μόνον Κωσταντῖνον ἀρχῆς, οὐκέτι λοιπὸν τὴν κατὰ φύσιν ἐνοῦσαν αὐτῷ κακοήθειαν ἔκρυπτεν, ἀλλὰ ἐνεδίδου τῷ κατ’ ἐξουσίαν ἅπαντα πράττειν. ἐχρῆτο δὲ ἔτι καὶ τοῖς πατρίοις ἱεροῖς, οὐ τιμῆς ἕνεκα μᾶλλον ἢ χρείας· ᾗ καὶ μάντεσιν ἐπείθετο, πεπειραμένος ὡς ἀληθῆ προεῖπον ἐπὶ πᾶσι τοῖς κατωρθωμένοις αὐτῷ. ἐπεὶ δ’ εἰς τὴν Ῥώμην ἀφίκετο μεστὸς πάσης ἀλαζονείας, ἀφ’ ἑστίας ᾠήθη δεῖν ἄρξασθαι τῆς ἀσεβείας. Κρίσπον γὰρ παῖδα τῆς τοῦ Καίσαρος, ὡς εἴρηταί μοι πρότερον, ἀξιωθέντα τιμῆς, εἰς ὑποψίαν ἐλθόντα τοῦ Φαύστῃ τῇ μητρυιᾷ συνεῖναι, τοῦ τῆς φύσεως θεσμοῦ μηδένα λόγον ποιησάμενος ἀνεῖλεν. τῆς δὲ Κωσταντίνου μητρὸς Ἑλένης ἐπὶ τῷ τηλικούτῳ πάθει δυσχεραινούσης καὶ ἀσχέτως τὴν ἀναίρεσιν τοῦ νέου φερούσης, παραμυθούμενος ὥσπερ αὐτὴν ὁ Κωσταντῖνος κακῷ τὸ κακὸν ἰάσατο μείζονι· βαλανεῖον γὰρ ὑπὲρ τὸ μέτρον ἐκπυρωθῆναι κελεύσας καὶ τούτῳ τὴν Φαῦσταν ἐναποθέμενος ἐξήγαγεν νεκρὰν γενομένην.
(Zosimus, Historia Nova 2.29.1-2)
Now that the whole empire had fallen into the hands of Constantine, he no longer concealed his evil disposition and vicious inclinations, but acted as he pleased, without controul. He indeed used the ancient worship of his country; though not so much out of honour or veneration as of necessity. Therefore he believed the soothsayers, who were expert in their art, as men who predicted the truth concerning all the great actions which he ever performed. But when he came to Rome, he was filled with pride and arrogance. He resolved to begin his impious actions at home. For he put to death his son Crispus, stiled (as I mentioned) Caesar, on suspicion of debauching his mother-in-law Fausta, without any regard to the ties of nature. And when his own mother Helena expressed much sorrow for this atrocity, lamenting the young man’s death with great bitterness, Constantine under pretence of comforting her, applied a remedy worse than the disease. For causing a bath to be heated to an extraordinary degree, he shut up Fausta in it, and a short time after took her out dead.
(tr. W. Green & T. Chaplin)