Cassius Dio, Roman Histories 2.11:
“Tarquinius, when he was sufficiently prepared to tyrannize over them even against their will, did away with the most powerful people in the senate, and then in the population at large; he killed many openly if he was able to come up with some suitable charge for them, but he also killed many in secret and banished some. He did this not just because some of them loved Tullius more than him, nor because they had breeding and wealth or wisdom, nor because they were endowed with manifest bravery and wisdom; he killed from envy and suspicion because they were dissimilar in character, but, no less than the rest, he also killed many of his friends who had helped put him in power, reckoning that on account of their boldness and eagerness for revolution, through which they had helped him, they could easily give the throne to someone else.
Thus he killed off the strongest part of the senate and the equestrian class, nor did he replaced any of the people who were killed. He knew that he was hated by the entire populace, and he wished to make them as weak as possible through lack of manpower. He undertook to completely dissolve the senate and every gathering of people, especially one of chosen people and of anyone who had a pretext to authority from antiquity, because he reckoned that these meetings were necessarily extremely hostile to the tyrant.”
ὁ Ταρκύνιος ἐπεὶ ἱκανῶς ὡς καὶ ἀκόντων τυραννήσων παρεσκευάσατο, τοὺς δυνατωτάτους πρῶτον μὲν τῶν βουλευτῶν ἔπειτα καὶ τῶν ἄλλων συλλαμβάνων, πολλοὺς μὲν φανερῶς, οἷς γε αἰτίαν τινὰ εὐπρεπῆ ἐπενεγκεῖν ἐδύνατο, πολλοὺς δὲ καὶ λάθρᾳ ἀπεκτίννυε καί τινας ὑπερώριζεν. οὐ γὰρ ὅτι τὸν Τούλλιόν τινες αὐτῶν μᾶλλον ἢ ἐκεῖνον ἠγάπησαν, οὐδ’ ὅτι γένη καὶ πλούτους ἢ καὶ φρόνημα εἶχον, ἀνδρείᾳ τε ἐπιφανεῖ ἢ καὶ σοφίᾳ διαπρεπεῖ ἐχρῶντο, τοὺς μὲν ἀμυνόμενος τοὺς δὲ προκαταλαμβάνων, φθόνῳ τε καὶ ὑποψίᾳ ἅμα μίσους ἐκ τοῦ μὴ ὁμοήθους ἔφθειρεν, ἀλλὰ καὶ τοὺς πάνυ φίλους πρός τε τὴν μοναρχίαν οἱ σπουδάσαντας οὐδὲν ἧττον τῶν ἑτέρων ἀπώλλυεν, νομίζων σφᾶς ὑπό τε τῆς θρασύτητος καὶ ὑπὸ τῆς νεωτεροποιίας, ὑφ’ ἧς ἑαυτῷ τὴν ἀρχὴν συγκατέπραξαν, κἂν ἄλλῳ τινὶ αὐτὴν δοῦναι. κἀκ τούτου τὸ κράτιστον τῆς βουλῆς καὶ τῆς ἱππάδος ἀπανάλωσεν, οὐδ’ ἀντικαθίστη τὸ παράπαν ἐς αὐτοὺς ἀντὶ τῶν ἀπολλυμένων οὐδένα· μισεῖσθαί <τε> γὰρ ὑπὸ παντὸς τοῦ δήμου ἐπίστευε, καὶ τὰ τέλη ἐκεῖνα ἀσθενέστατα ἐκ τῆς ὀλιγανθρωπίας ποιῆσαι ἐπεθύμει. καὶ τήν γε γερουσίαν καὶ καταλῦσαι παντελῶς ἐπεχείρησεν, πᾶν ἄθροισμα ἀνθρώπων, ἄλλως τε καὶ ἐπιλέκτων καὶ πρόσχημα προστατείας τινὸς ἀπὸ παλαιοῦ ἐχόντων, πολεμιώτατον τυράννῳ νομίζων εἶναι.