[TRYPHONINUS libro primo disputationum. ] §11.4.5.prSi in harenam fugitiuus seruus se dederit, ne isto quidem periculo, discriminis uitae tantum, sibi irrogato potestatem domini euitare poterit: nam diuus Pius rescripsit omnimodo eos dominis suis reddere siue ante pugnam ad bestias siue post pugnam, quoniam interdum aut pecunia interuersa aut commisso aliquo maiore maleficio ad fugiendam inquisitionem uel iustitiam animaduersionis in harenam se dare mallent.
[TRYPHONINUS, from the first book of Discussions.] If a runaway slave should surrender himself to the arena, he will not be able to escape the power of his master, even though that danger, namely of life alone, is imposed on him; for the deified Pius wrote in a rescript that they must by all means be returned to their masters, whether before the fight with beasts or after the fight, since sometimes, either because they have embezzled money or committed some greater crime, they would prefer to surrender themselves to the arena in order to escape investigation or the justice of punishment.
reddi ergo eos oportet.
Therefore, they must be returned.