The Russian embassy in Colombia confirmed in a Facebook post the death of Armenian citizen Arsen Voskanyan who disappeared in November 2016.
The Russian mission assumes that he died while trying to escape from captivity.
Earlier, Voskanyan's brother, Armen Voskanyan, rejected the information as outdated, "which the media periodically publish in search for a sensation."
Voskanyan had been held by Resistance Front Cimarron ELN since November 2016. According to Colombian authorities, Voskanyan was the only foreigner held by the guerrilla group in that part of the country.
The Armenian, as authorities assume, was kidnapped in Pizarro, Chocó where he was looking for golden frogs, an endemic species, in an apparent attempt to illegally ship them out of the country.
Golden frogs produce deadly toxin used in laboratories across Europe to manufacture painkillers. They are sold by up to 1,500 euros each on the black market.