Did Russia use a dart frog toxin to kill Alexei Navalny? How deadly is this poison?

Two years after the death of Alexei Navalny, five European nations have claimed that Russia used epibatidine, a poison derived from dart frogs, to kill the prominent Kremlin critic. This neurotoxin, more potent than morphine, can cause muscle twitching, paralysis, seizures, slow heart rate, respiratory failure and ultimately death