I am a delivery person for a sub shop. Tonight i made a delivery and i accidently overheard the convo...?

in the backgrnd..which I wished to god i NEVER overheard.But this guy was bragging how he had shot 2 cats that live in a barn in the head and said "It was perfect." My jaw dropped. I quickly left in shock w/my heart at the bottom of my stomoch. I was so appalled about the wah he bragged about this. That i called him back on my cell and called him a murderer. and that i was reporting him to the humane society. We just my word vs his ( which he will probably deny) is there anything legal i can do? Those poor innocent kittys. I love cats i have a cat i rescued. and i imagined this guy shooting him in the head. I bawled all teh way back to teh store. And when i arrived the my shift leader was on the phone w/this guys gf. and she was complaining how she felt violated that i * overheard* there convo! I may get fired over this. Can u believe it. I just want this person to have sum kind of punishment. Anyone know the legalities of a situation like this . Please help. Can they fire me?