Sergei Ovchinnikov, who coached the Russian women's volleyball team at the London Olympics, has reportedly committed suicide.
He was 43.
"Sergei Ovchinnikov suddenly passed away at the team's [pre-season] training camp in Croatia," Dynamo Moscow said on their website.
He had combined his job with the Russian team as head coach of Dynamo Moscow.
There was no cause of death given but it was widely reported Ovchinnikov among the Russian media that he had commited suicide, possibly as a result of Russia's disappointing performance at London 2012.
Ovchinnikov had been appointed coach of Russia's team and they were considered to be among the favourites for the gold medal having won the World Championships in 2006 and 2010.
But they were knocked out in the quarter-finals to eventual winners Brazil after squandering six match points.
"He took the Olympics very personally," Vladimir Alekno, the head coach of Russia's men's team who won the gold medals at London 2012, told Interfax, the Russian news agency.
"I saw what he was going through and how upset he was after the defeat.
"He didn't talk much.
"Even after victories he was always thinking about something and smoked a lot."
Alexander Yaremenko, the general director of the All-Russian Volleyball Federation, was unable to confirm the reports that Ovchinnikov had commited suicide.
"So far nothing's clear, all I can do is confirm the fact that he has died," he said.
By Duncan Mackay at the Main Press Centre on the Olympic Park in London