That said in the Caucasus there is a great deal of homogeneity among the people. Cultural whatever. It's not something you can get if you have not spent time there, perhaps but I have and it is amazing.
I understand very much that Chechens can be and are a dangerous people.
I am under no illusions about them.
However, the good guys have rules even though the bad guys operate with no rules at all.
That gives the bad guys a very clear advantage.
As soon as the good guys break the rules, even if it is to get to the baddest of the bad, then they are no longer the good guys, and the bad guys won, because their ranks have just been added to.
If the FBI agent murdered this man and then lied about the circumstances, he must be kicked out of the good guys and made to answer for his crimes.