Reish Lalish killed the Gladiators

  Gittin (47a) Reish Lakish sold himself to gladiators. He took a bag and a round stone inside of it with him. He said: There is a tradition that on the final day of a captive’s life, before his captors kill him, they do for him anything that he requests of them, so that he would forgive them for the spilling of his blood. On the final day before they were set to kill him they said to him: What is amenable to you? He said to them: I want to tie you up and have you sit, and I will strike each one of you one and a half times. He tied them up and had each one of them sit. When he struck each of them with one strike with the stone in the bag, the one whom he struck died, because Reish Lakish was of great strength. Reish Lakish gritted his teeth in anger, and said to the one whom he killed, in order to prevent the others from realizing what was happening: Are you laughing at me? You still have half of a strike remaining with me, as I struck you only once. He killed them all, and Reish Lakish escaped his captors. He left and came back home, and after some time had passed he was sitting, eating, and drinking, without concern for his livelihood. His daughter said to him: You don’t want something to lie upon? He said to her: My daughter, my belly is my pillow, and this is enough for me. When he died he left only a kav of saffron as an inheritance, and even so he recited this verse about himself: “And they leave their wealth for others” (Psalms 49:11), meaning that he was pained that he did not use all of his property. He exhibited his confidence that God would provide his needs by not saving money for the future. 

Rav Tzadok (Takanas Hashavim 9) The nature of Reish Lakish’s criminal past is not mentioned at all in the Talmud since it had already been repented and thus was no longer considered that he had sinned at all. It appears to me that the story that he sold himself to gladiators and killed all of them is also not regarded as sinful as Tosfos states there since this happened before he did teshuva, However it is not clear why this event was mentioned in the Talmud especially since it seems like he was going to be killed by the gladiators according to the customs of those times and thus it was tantamount to suicide. It is thus obvious to me  that all his actions were done deliberately for the sake of Heaven for the sake of repentance because there are views that suicide and self induced suffering is an appropriate way of teshuva.