I'd imagine they had a electronic shooting platform of some kind in the area of the tower. A body would have been seen. One shot was true. Freak miss by a well aimed shot. Think Shtr movie intermingled w a schizo that they surveilled and allowed to act as cover.
Is the only scenario that plays as far as I see it so far.
No that very expendable asset has now become a liability and will need to be done away w before new admin takes over. On the flipside a certain leader in Russia may demand it in order to start anew under current borders during the new admin. So his future is sorta fkd no matter how this plays out. That guy probably trafficked as many kids as Mother Teresa. Don't feel sorry for him. We won't know who did it. Both sides want him.
I'd expect something subtle due to the complexity of it. Id say whoever ends up tasked w it is probably thinking an od would play most effectively lol. I don't condone violence I just know how these ppl work.
Or Tristan Da Cuhna