The boss of a Russian crime gang was serving a 23-year jail term when he requested to fight in Ukraine.
He went to the frontline by the shadowy Wagner Group, who had been recruiting prisoners to fight.
Igor Kusk died after being hit in the head by shrapnel while fighting in the Donbas region.
A Russian crime boss who was serving a 23-year jail term before leaving prison to fight in Ukraine was killed in action, according to the Russian outlet Business Gazeta.
Igor Kusk was the leader of a gang in Tatarstan and was found guilty of various crimes, including murders in 2015, and was imprisoned in a strict regime prison colony, according to reports.
Kusk sent a letter from prison to the leader of Chechnya, Ramzan Kadyrov, asking to join the fight in Ukraine, his widow Irina told the outlet.
A representative from the paramilitary Wagner Group came to get him, and she said he was sent to the front line on July 25.
He died on September 6 fighting in the Bakhmut region in the Donbas from a shrapnel injury to the head, said the report.
Irina said her husband was 55 and not in perfect health but was not afraid of anyone. Kusk had previously served in the Soviet-Afghan War, it was reported.
Numerous photos of the Kusk's funeral in a village near Kazan, 500 miles east of Moscow, appear to show it was attended by hundreds of mourners, including local officials.
Men in military uniform fired three volleys into the air from machine guns. The former crime lord was buried in the "walk of fame" of the city cemetery alongside other soldiers killed in Ukraine, and photos show his grave adorned with large bouquets, reported Business Gazeta.
A video recently surfaced of Yevgeny Prigozhin, the head of the shadowy Wagner Group and a close Putin ally, recruiting men at a Russian prison to fight in Ukraine.
Prigozhin promised them freedom if they served for six months but warned that they would be killed if they tried to desert.
Kusk's presence in Ukraine suggests that Wagner took recruits from prison as early as July.
The Wagner group is variously described as a mercenary outfit, a private military contractor, and Putin's private army.
It has close links to the Kremlin, and its soldiers have been linked to a massacre in Bucha, Ukraine, and accused of committing war crimes in Africa.
The group, which has also seen action in the Syrian civil war, has been tied to Russian separatists in the pro-Russian Donbas region since 2014.