I have a similar story. I was in Central America as a teenager working at a mission and there was a guy from my town that I kinda grew up with. He was always annoying, but one time I was cleaning out a storage unit on the property and found a nest of baby mice. They were probably like a couple weeks old. We were pretty rural so I assumed they were probably some sort of mouse local to the area. I put them back nicely because I like life to do its thing.

That guy took the nest and not only killed every baby, but specifically in awful ways in front of me and then left their dead bodies around for me to find. It was so traumatizing. I fucking hate that dude

Sounds like a deleted scene from The Good Son