In a stunning revelation, European nations have accused the Kremlin of poisoning Alexei Navalny, a prominent Russian opposition figure, with a rare toxin derived from poison dart frogs. This assertion was made jointly by five countries on Saturday.

The foreign ministries from the United Kingdom, France, Germany, Sweden, and the Netherlands have reported that detailed analysis of Navalny’s biological samples has “definitively identified” epibatidine, a potent neurotoxin typically found in the skin of South American dart frogs, as the substance involved. This toxin, notably absent from the Russian natural environment, was pinpointed in their investigation.

In a collective statement, these nations asserted that Russia had both the capability and motive to execute such a poisoning. They are now prepared to report Russia to the Organization for the Prohibition of Chemical Weapons, accusing it of violating the Chemical Weapons Convention.

This disclosure coincides with Navalny’s widow, Yulia Navalnaya, attending the Munich Security Conference in Germany. The timing is poignant as the second anniversary of Navalny’s demise draws near.

Navalny, renowned for his fight against governmental corruption and his role as a leading critic of President Vladimir Putin, died on February 16, 2024, while imprisoned in a penal colony in the Arctic. He was serving a 19-year sentence, which he and his supporters deemed politically driven.

“The Russian government viewed Navalny as a significant threat,” remarked British Foreign Secretary Yvette Cooper. “The use of such an exotic poison underscores the alarming measures the Russian state is willing to employ and highlights its acute fear of political dissent.”

Navalny’s widow, said last year that two independent labs had found that her husband was poisoned shortly before he died. Navalnaya has repeatedly blamed Putin for Navalny’s death, something Russian officials have vehemently denied.

Navalnaya said Saturday that she had been “certain from the first day” that her husband had been poisoned, “but now there is proof.”

“Putin killed Alexei with chemical weapon,” she wrote on social network X, calling Putin “a murderer” who “must be held accountable.”

Russian authorities said that the politician became ill after a walk and died from natural causes.

Epibatidine is found naturally in dart frogs in the wild, and can also be manufactured in a lab, which European scientists suspect was the case with the substance used on Navalny. It works on the body in a similar way to nerve agents, causing shortness of breath, convulsions, seizures, a slowed heart rate and ultimately death.

Navalny was the target of an earlier poisoning in 2020, with a nerve agent in an attack he blamed on the Kremlin, which always denied involvement. His family and allies fought to have him flown to Germany for treatment and recovery. Five months later, he returned to Russia, where he was immediately arrested and imprisoned for the last three years of his life.

The U.K. has accused Russia of repeatedly flouting international bans on chemical and biological weapons. It has accused the Kremlin of carrying out a 2018 attack in the English city of Salisbury that targeted a former Russian intelligence officer, Sergei Skripal, with the nerve agent Novichok. A British inquiry concluded that the attack “must have been authorized at the highest level, by President Putin.”

The Kremlin has denied involvement.