German doctors treating Pyotr Verzilov have said that the anti-Kremlin activist was probably poisoned, and a Moscow newspaper reports a possible connection with the killing of three Russian journalists in the Central African Republic (C.A.R.) in July.
The developments on September 18 deepened the mystery surrounding the sudden illness of Verzilov, a member of the punk protest band Pussy Riot and the dissident art troupe Voina who was flown to Berlin for treatment three days earlier.
"The impression and the findings that we now have, as well as those provided by colleagues from Moscow, suggest that it was highly plausible that it was a case of poisoning," Kai-Uwe Eckardt, a doctor at Charite hospital in Berlin, told a news conference.
Eckhart's colleague, Karl Max Einhaeupl, said that there was so far no other explanation for Verzilov's condition and no evidence that the activist, who was initially hospitalized in Moscow, was suffering from a long-term illness.
Eckardt said Verzilov's condition was not life-threatening. He said the symptoms indicated a disruption of the part of Verzilov's nervous system that regulates the internal organs, but that the substance responsible for the poisoning hadn't yet been determined.
Verzilov, 30, fell ill on September 11 after a court hearing in Moscow, and later suffered seizures while being taken to a hospital in an ambulance. Friends said he began losing his sight, speech, and mobility.
The Reuters news agency quoted Jaka Bizilj, the managing director of the Berlin-based Cinema for Peace human rights group, as saying his group had paid for Verzilov's flight to Berlin and that Russia had been "cooperative."
Bizilj said that Verzilov suffered seizures while being taken to a Moscow hospital by ambulance.
Verzilov's ex-wife, Pussy Riot member Nadezhda Tolokonnikova, told the German newspaper Bild he believed he was "poisoned intentionally, and that it was an attempt to intimidate him or kill him."
Footage posted by Tolokonnikova showed Verzilov sitting up in the plane on the tarmac in Berlin and he appeared to be alert.
In a September 18 report the independent Russian newspaper Novaya Gazeta said that on the day he was hospitalized, Verzilov was to have received a report from "foreign specialists" investigating the killings in C.A.R.
Russian journalists Orkhan Dzhemal, Aleksandr Rastorguyev, and Kirill Radchenko, were killed on July 30 in C.A.R., where they were working on a documentary about the possible activities there of a shadowy Russian paramilitary group with alleged Kremlin ties.
The Novaya Gazeta report, which cited sources it did not name, said that Verzilov was a close friend of Rastorguyev and had himself been planning to travel to C.A.R. with the trio but decided to remain in Russia to support jailed Kremlin opponents.
Verzilov is a co-founder of the website Mediazona, which reports on the trials of Russian activists, prison conditions, and other aspects of the Russian justice system. He has both Russian and Canadian citizenship.
In July, he was sentenced along with other Pussy Riot members to 15 days in jail for briefly interrupting the July 15 World Cup final in Moscow between France and Croatia by running onto the field wearing fake police uniforms.
Verzilov became known as a member of the Voina (War) art troupe in the late 2000s.
He performed with then-wife Tolokonnikova, who went on to form Pussy Riot with Maria Alyokhina and Yekaterina Samutsevich.
Alyokhina and Tolokonnikova founded Mediazona in 2014, with Verzilov becoming publisher.
Kremlin critics accuse the Russian authorities of poisoning several journalists, Kremlin foes, and others who have died or fallen mysteriously ill since President Vladimir Putin came to power in 2000.
Verzilov's sudden illness came against the backdrop of outrage over what British authorities say was the poisoning by Russian military intelligence officers of former Russian spy Sergei Skripal and his daughter with a nerve agent in England in March, and the death of a woman police say was exposed to the substance after the alleged attackers discarded it.