Ammianus Marcellinus Res Gestae 28.1.57

[57] But the final curses of his victims did not sleep. For, under Gratian, as shall be told later at the proper time, ¹ not only did this same Maximinus, because of his intolerable arrogance, fall victim to the executioner’s sword, but Simplicius also was beheaded in Illyricum. Doryphorianus, too, was charged with a capital crime and thrown into the prison called Tullianum, ² but Gratian, at the suggestion of his mother, had him taken from there, and on his return home put him to death with tremendous tortures. But let us return to the point from which we made this digression. This, if I may say so, was the state of affairs in Rome. ³