Vlad Putin would have tied him to a stake in the middle of a pig pen and slowly fired away at him for hours with .22 rounds.
The ones that were left alive after the Bolshoi Theatre attack were taken to Lubyabka. They weren’t heard of again, but the KGB leftovers there knew of how to deal with those types.
If ISIS really wants to go after Russia, Russia will use tactical nukes like we should have after 9/11. And they will take them to Lubyanka which will make gitmo seem like paradise.