On PRI's radio program The World, host Lisa Mullins interviews Roman history professor Michael Carter, of Brock University in Ontario, about the life and death of Roman gladiator Diodorus, who died in the 3rd century CE.
Carter's study is based on the discovery of the gladiator's tombstone which depicts the "end of a gladiatorial conflict between two gladiators. One gladiator stands victoriously over his opponent. He is holding two swords, and his opponent is on the ground, begging for mercy, no weapon in his hand."
A LiveScience article shows a closeup of the tombstone.