It seems like the popular opinion is that TT murdered his friend and the other two men, so of course I have to offer an alternative theory. I won't debate it's validity though, because I'm not sure how much I believe in its probability.
If TT had already started spending more time with radical Muslims, is it possible that one or more of them strongly disliked him being friends with a "friend of Jews", and possibly even spending time with the two Jewish men at times? I've been thinking that killing his only American friend, and making him look suspicious, might be a good way to show him how bad Americans are - murdering his best friend and accusing him of doing it. Once he got to Russia, they could really start to fill his head with more anti-American propaganda. If his mother/parents were also telling him similar things, it would make it even easier to convince him.
:shush: