Azov Brigade soldier Oleksandr Ishchenko has died in Russian captivity, Ukraine's Ombudsman Dmytro Lubinets, said on July 31.
In a post on Telegram, Lubinets said Kyiv had not been officially informed of the death but Ishchenko's daughter confirmed the news, saying he passed away nine days ago.
The cause of his death is not yet currently known.
Ishchenko was 55-years-old and a native of Mariupol, Ukrainska Pravda reported. He joined the Azov Brigade as a driver shortly after the launch of Russia's full-scale invasion.
He was captured while fighting in Mariupol in 2022.
Lubinets said he had contacted the Commissioner for Human Rights in the Russian Federation for information on the "circumstances and cause of Oleksandr Ishchenko's death."
"Let me remind you that according to Article 12 of the Geneva Convention on the Treatment of Prisoners of War, prisoners of war are in the hands of an enemy state and not of individuals or military units that captured them," he said.
"Regardless of the responsibility that individuals may bear, the detaining power is responsible for the treatment of prisoners of war."