The public appeal -- signed by such luminaries as Lyudmila Alekseeva of the Moscow Helsinki Group, Aleksandr Cherkasov of Memorial, Lev Ponomarev of For Human Rights, and the liberal clergyman Gleb Yakunin -- called on the anti-fascist groups (who call themselves Antifa) "not to succumb to provocations, to renounce violence, and not to become a bargaining chip in a dirty game."
They warned that violent retaliations against nationalists would "give law enforcement authorities a pretext for new repressions," which may have been "the goal of provocateurs."
The rights activists spoke out in the hyper charged atmosphere following the shooting death of Antifa leader Ivan Khutorskoi, a former punk rocker known by his nickname "The Bonebreaker." Khutorskoi was shot twice in the back of the head in the stairwell of his Moscow apartment building on November 16.
Antifa groups responded the next day by attacking the office of the pro-Kremlin youth group Young Russia, pelting the building with stones, trash, and steel rods. Antifa activists say Young Russia has close ties with Russky Obraz, an ultranationalist group they believe was behind Khutorskoi's killing.
A social worker by profession, Khutorskoi was known for organizing underground bare-knuckle boxing matches. He also provided security for Antifa events, as well as sometimes for human rights lawyer Stanislav Markelov's press conferences.
Khutorskoi, however, was not present at Markelov's press conference in January, after which the lawyer and "Novaya gazeta" journalist Anastasia Baburova were shot dead.
Prior to his death on Monday, Khutorskoi had reportedly survived attempts to kill him -- once with a knife, once with a razor, and once with a screwdriver.
Antifa activists said nationalist groups had been posting Khutorskoi's address on the Internet and encouraging attacks against him.
Aleksandr Verkhovsky, director of the Sova Center, a watchdog group that monitors racial attacks, told "The New York Times" that Antifa groups have recently begun adopting the tactics of their enemies, carrying out attacks against known nationalists.
-- Brian Whitmore