Russian state media beginning to speculate that these were Russia Volunteer Corps fighters in fake beards. Suuuurrrrreee.
“Who committed this attack, the result of which according to incomplete information from the FSB over 60 people died and 140 were injured, and why is still unknown. (The figures will grow, of course.) Some sources have proposed that the terrorists could have been members of the banned in Russia organization “Russian Volunteer Corps.” Its members periodically attack populated outposts in Russian oblasts bordering Ukraine. On the eve of the terror attack the FSB arrested a group of supporters planning to fight in Ukraine and in the meantime planning minor diversion in Russia.
Tonight security forces began receiving orienting information from the operational HQ to carry out the search for the attackers. In them, according to source “B,” it was written that the terrorists are young people, taller than average, up to 180 cm, possibly wearing fake beards and mustaches.”
https://www.kommersant.ru/doc/6592262