The place could had something to do with his behaviour, but I think that it didn't change him at all. The experiences with people while the years passed, the maturity, what he started to see about the world and in the school and his interests could influenced too because he wasn't violent immediately after moved to Colorado.
_________________
The most terrifying fact about the universe is not that it is hostile but that it is indifferent; but if we can come to terms with this indifference and accept the challenges of life within the boundaries of death — however mutable man may be able to make them — our existence as a species can have genuine meaning and fulfillment. However vast the darkness, we must supply our own light