Cherepanov, considered one of Russia's most promising hockey stars, collapsed and later died on October 13 after playing for the Omsk Avangard club at a match in the Moscow Region.
The website of the Investigation Committee of the General Prosecutor's Office said the paramedics, who arrived 12 minutes after the emergency call, had a defibrillator with a low battery. The investigators said the paramedics also incorrectly pronounced his "natural death."
The committee said in a statement a team of medical investigators had established that Cherepanov was suffering from chronic myocarditis which meant he should not have been playing sport.
"The death was directly caused by a serious cardiovascular condition. No traces of alcohol or drugs were found in his blood and urine, however, tests for chemicals showed that Alexei Cherepanov had been using stimulants for several months," the statement reads.
Regional prosecutors in the Moscow Region said in early December that a hockey club director, who has already been sacked, and an ice arena manger had failed to coordinate emergency medical services before the game.
Nicknamed the Siberian Express, Cherepanov was born in Russia's Altai Territory, in the city of Barnaul in 1989. He had played two seasons as a professional, beating in March 2007 the Russian league goal-scoring record for rookies previously held by the legendary Pavel Bure.
He was expected to follow in Bure's footsteps and move to the National Hockey League, having been the New York Rangers' first-round pick in the 2007 NHL draft.