That changed their 'attitude', rather quickly, and would explain why Tamerlan quit going to the gym.
Could well be.... hope this is investigated HARD.....
If the handlers did the hit they might have first made sure that Tamerlan and his brother had ironclad alibis so that nothing could possibly point to them..... it will be interesting to learn whether police looked at that aspect and if Tamerlan did in fact have a tight alibi.