A former aide to Russian President Vladimir Putin died from blunt force trauma to the head in a Washington hotel room, an autopsy has shown.
Blunt force injuries to the neck, torso, arms and legs also contributed to Mikhail Lesin’s death, the District of Columbia’s Medical Examiner’s Office said.
Russian media had previously cited relatives when reporting he had suffered a heart attack.
The 57-year-old, who died on 5 November, was a media adviser to Mr Putin and helped found the English-language news service Russia Today.
Police were called to Mr Lesin’s room at the Dupont Circle Hotel after concerns about his welfare.
He was found unresponsive on the floor and pronounced dead at the scene.
A US law enforcement source told the Reuters news agency the investigation into Mr Lesin’s death was being led by Washington DC police.
They are investigating whether Mr Lesin was brutally assaulted before he returned to the hotel.
When police first investigated the room where his body was found, they did not find any damage or evidence indicating foul play.
A spokesman for the Russian Embassy in the US said officials have requested information on the investigation for several months.
Press secretary Yury Melnik said: “No substantial information has been provided. With regard to the document that has been released to the public today, we expect the American side to provide us with relevant official explanation.”
Mr Lesin pressed to establish the Russia Today satellite TV channel, later renamed RT, once saying Russia “must do propaganda for ourselves, otherwise we’ll always look like bears”.
He served as Russian press minister from 1999 to 2004 and presidential media adviser from 2004 to 2009, according to RT.
He later became head of Gazprom-Media, Russia’s largest media holding company, in 2013 but resigned the following year.