A former top Kremlin aide who was found dead in a Washington hotel room last year, died of "blunt force injuries" to the head, authorities have said.

Washington's chief medical examiner said Mikhail Lesin, who was 57, had suffered injuries to the neck, torso, arms and legs and the city's police is continuing its investigation.

He was found dead in a hotel room in November 2015 in Washington's Dupont Circle and much of Russian media quoted family members saying he died of a heart attack.

However many conspiracy theories arose among Russian journalists and opposition figures who questioned why he was in Washington and why a member of Russia's political elite was staying in only a mid-range hotel.

Before his death, the Mississippi Senator Roger Wicker had called on the US Department of Justice to investigate if Lesin's alleged purchase of exclusive homes in Los Angeles violated the Foreign Corrupt Practices Act and raised questions over whether the purchase involved people and groups on a US sanctions list.

Lesin was one of the most influential figures on the Russian media scene, serving as Russia's media minister first under Boris Yeltsin then under Vladimir Putin until 2009.

He headed Gazprom Media and managed the takeover of private TV channels ensuring they were carefully controlled by the state. He also helped create Russia Today, now known as RT, the Kremlin-funded international news channel.

Washington police spokesman Dustin Sternbeck said the case remained under investigation but did not say if the post-mortem results meant there had been foul play, the Washington Post reported.

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