Russian
I don't see why the FBI doesn't contact the Russian government to collaborate on this.
The US State Department and the FBI, have stumped up $3m in reward money for the arrest of Evgeniy Mikhailovich Bogachev, the 30-year-old Russian man accused of stealing over $100m with his malware. Russian wanted by FBI Have you seen this man? Bogachev, who operated under the aliases "lucky12345," "Slavik," and " …
...in my view, comprises, "Eastern Ukraine", "Consequent Sanctions", "Saudi Flooding (pardon the expression) the Oil Market (no doubt in orchestration with NATO in general and the U.S. in particular)", "Consequent Collapse of Ruble", and "Consequent Double-Digit Inflation in Russia".
So, I would not bet the FSB would cooperate a bit with the FBI.
Moreover, in my view, probably, Bogachev is a Putin-o-crony-klepto-crat bringing international hard currency to the State Treasury badly-needed even when the Monopoly-Game ruble is *not* in collapse.
Were I in Petersburg, I would not be surprised to hear all the way from the Lubyanka in Moscow the FSB's laughter greeting any FBI assistance request.