(JTA) – The murder of former deputy prime minister Boris Nemtsov risked plunging Russia into civil war, Russian dissident Mikhail Khodorkovsky said.

An unidentified shooter on Saturday, Feb. 28, gunned down Nemtsov, a leading opposition politician in Russia. Nemtsov was a Christian but said he had Jewish ancestry.

Khodorkovsky, a Russian Jew who left for Switzerland in 2013, made the warning in a statement posted Saturday on his website. The dissident, who was sentenced to 11 years in prison following graft trials that critics alleged were designed to eliminate his political ambitions and criticisms of human rights abuses by Russian President Vladimir Putin, noted that Nemtsov was gunned down “a hundred meters from the Kremlin.”

Nemtsov died hours after appealing for support for a march in Moscow against the war in Ukraine.

“I know that for many people Boris’s death will become so much of a Rubicon that the entire country may become different,” Khodorkovsky wrote on his website. “Will we find ourselves standing even closer to the precipice of all-out war of everybody against everybody? Or will we find within ourselves the strength to understand that political differences are not a reason to stop acting like human beings?”

Putin condemned the murder and said he was closely monitoring the investigation amid widespread speculation that Nemtsov was eliminated by the Kremlin, as were other dissidents before him.

Leonid Bershidsky, a Russian Jewish journalist, in an Op-Ed published on bloombergview.com criticized Putin’s government for what he said amounted to incitement against Nemtsov, writing that Nemtsov’s name was “on every list of traitors published on the Internet and aired on state TV.”

“It did not help that he was Jewish,” he wrote. “There was a strong undercurrent of anti-semitism in the smear campaign.”