The mystery of the death of Mikhail Lesin deepened this week after new reports emerged from the US about how he died.

In November, Lesin was found dead in a Washington, D.C. hotel room. Russian state media quoted his family at the time as saying that the 57-year-old had died of a heart attack.

But, on Thursday, a US medical examiner said that the former Putin aide had died from blunt force trauma to his head. The examiner also said he had blunt force injuries to his neck, torso, arms and legs.

Moscow waiting for answers

After the news was released, Maria Zakharova, spokesperson for the Russian Foreign Ministry, wrote on Facebook that the Russian Embassy in Washington had repeatedly requested information about the circumstances of Lesin's death but had not received anything.

"We are waiting for clarification from Washington and the relevant official details on the progress of the investigation," Maria Zakharova said.

She continued by saying: "If the information published today by the media is true, the Russian authorities will send a request for international legal assistance to their American counterparts."

Dmitry Peskov, spokesperson for Vladimir Putin, also said the Kremlin was awaiting official information from the Americans.

Mikhail Lesin previously led the powerful Gazprom Media group and was a Russian press minister.

Media mogul

In his role as head of Gazprom Media from 2013 to 2014, Lesin was considered to be one of the most powerful people in the Russian media scene. The group itself is owned by a company in which the Russian government has a controlling stake.

Lesin also advised the presidency on the creation of Russia Today (RT), Russia's English-language news channel which was launched 10 years ago and is funded by the Kremlin.

Before his death, Lesin was suspected of corruption and money laundering, with Republican senator for Mississippi, Roger Wicker, calling for an investigation into the Russian media mogul in 2014. He allegedly amassed millions of dollars in assets in Europe and the United States while working for the Russian government, including 25 million euros ($28 million) in real estate in Los Angeles.

"That a Russian public servant could have amassed the considerable funds required to acquire and maintain these assets in Europe and the United States raises serious questions," Wicker said at the time.

Not the first mysterious death

Mikhail Lesin is not the first Russian to die in apparently unusual circumstances.

Nikita Kamaev, the former head of the Russian anti-doping organization, Rusada, died in January 2016, aged 52. Rusada said he died from a heart attack, but British and German media reported he had been planning to publish a revealing book about doping in Russian sports.

His death came two weeks after that of Vyacheslav Sinev, the founding chairman of Rusada. Russia has been provisionally suspended from international athletics and Rusada had been banned from carrying out any anti-doping related activity following the publication of a World Anti-Doping Agency report which alleged "state-sponsored doping." There is currently no suggestion of foul play over his death.

UK cases

In 2013, Russian oligarch Boris Berezovsky was found dead in a locked bathroom in his home in the United Kingdom with a ligature around his neck. A postmortem examination concluded that he had died from hanging with no signs of violent struggle.

Berezovsky was a former ally of President Putin who then fled into exile in London. Not long before his death he lost a high-profile court case against his former business partner, Roman Abramovich.

In November 2012, Alexander Perepilichny collapsed while running near his home outside of London. An inquest later learned that traces of a chemical which can be found in a plant were found in his stomach. He had sought asylum in the UK and was helping Swiss prosecutors investigate an alleged Russian money-laundering scheme.

Perepilichny also provided evidence against those linked to the death of Sergei Magnitsky, a lawyer who uncovered an alleged fraud scheme and who died in custody in Russia. Following the lawyer's death, the US adopted the Magnitsky Act, a bill cracking down on Russian corruption.

Alexander Litvinenko was killed in 2006 by radioactive polonium-210 which is believed to have been put in a cup of tea. The 43-year-old former KGB and FSB officer had fled to London where he was a fierce critic of the Kremlin. A public inquiry into his death concluded that President Putin "probably approved" his assassination. Russia reacted angrily to the report saying that the case had been "politicized."