I have a bad feeling about a classmate

So I just began school like a week ago, but today on my last course the teacher didn't come to the class so me and my classmates started chating and well basically doing nothing really.

But we at some point began to talk to this one dude who is like a "loner" or sum liek that, the thing is that my classmates asked him about the content that he likes like idk series and shit. the thing is that he told us that he likes history specially WW1 and WW2, it was all fine until he came out with an off puting comment about how he knows how to "maim" thigns and that he has done that shit to small animals like lizards.

I´m not sure abt what to do but I only know that I am not interacting with that dude, EVER.

(srry if I have a horrible grammar I don´t really know that much english)