Dmitry Bogatov is a math teacher and Debian maintainer who was arrested last week. As a precaution, Debian has revoked his keys. Details on the allegations against him can be found via meduza.io, "Mathematics teacher accused of inciting mass riots now also accused of supporting terrorism and once again detained."
Debian's brief statement on the matter can be found at Debian.org. The Tor Project has also issued a statement concerning Bogatov's arrest.