From as many "blunders" and outrageous acts, I have been questioning some of the reasons for quite some time now.
This is a pretty telling article.
https://www.bostonmagazine.com/news/2017/04/09/tamerlan-tsarnaev-fbi-informant/
This is a pretty telling article.
https://www.bostonmagazine.com/news/2017/04/09/tamerlan-tsarnaev-fbi-informant/