I agree. I think he should be extremely concerned about his son. Anyone who can show that type of cruelty to an innocent animal, will usually do much much worse to a human animal. It's a fact that most serial murderers abused animals first. It's scary.. I would avoid this co-worker but keep a close eye on him and his family.

Did they think it was a rat or mouse in the garage and feel bad about it afterwards or were they well aware of what they were doing?