Who is Vadim Krasikov, a Russian jailed in Germany and linked to a possible prisoner exchange?

Vadim Krasikov’s name has come up several times in recent weeks in relation to prisoner exchanges between Russia and Western countries. Associates of Russian opposition leader Alexei Navalny said Monday that talks were underway shortly before his death to exchange him for a Russian imprisoned in Germany. According to Maria Pevchikh, one of Navalny's closest associates, he and two U.S. citizens held in Russia were to be swapped for Krasikov. Her claims could not be independently confirmed and she did not offer any evidence to back them up.