Anthony Petrosky is a retired ODST trooper of the 105th Shock Troops Division. He was aboard the UNSC Atlas on April 22nd, 2525 and witnessed the recently augmented Spartan John-117 fight against 4 other ODSTS after a Sergeant ordered the 5 of them into a boxing ring to fight.
According to Petrosky, he was sparring in the gym of Atlas with his fellow Marines when they saw John in the gym. They asked him his name, but when he gave them attitude and then insults were thrown back and forth. A CPO then ordered them into the ring to fight and John killed two of the Helljumpers, caving one's face in and stopping the other's heart. The other two soldiers were taken to the hospital, and one never walked again.