Modern pentathlon world silver medallist Alexander Kukarin has died at the age of 22 following a suspected a heart attack.
The Russian athlete died on Thursday at a Moscow hotel, but the Russian Modern Pentathlon Federation only released a statement on Monday.
"We did not find any signs that he had been attacked, while there were no suspicious signs," it said.
Kukarin also won the Russian Cup and a bronze at the European Championships.
The federation's statement added: "The athletes have finished their season and Alexander was not at a training camp. An unexpected cardiac arrest is our initial diagnosis."