Sounds to me like the murder could have been designed to put Tamerlan in the right mindset.
I seem to recall that in writings #1 made before 2011 he lamented that he had no American friends. Furthermore, he further wrote that he did not understand Americans as well and because of this felt isolated.
This reeks of misinformation. The Uncle who appears to be so indignant of his nephew’s actions needs to be investigated as well.