The documents from the city's medical examiner were released to Radio Free Europe/Radio Liberty in response to a Freedom of Information Act lawsuit filed nearly two years ago.

In a report published on Saturday, RFE said the finding offers no clear-cut evidence of foul play in the death of Mikhail Lesin, who was a key adviser to Russian President Vladimir Putin during Putin's rise to power.

But RFE said the documents provide "the most precise scientific description" yet of a death that's been shrouded in suspicion.

The official ruling was that Lesin, 57, died accidentally of blunt force trauma after falling repeatedly in his room while intoxicated.

Yet there is intrigue surrounding the case, fed by circumstantial evidence: It seems odd for someone Lesin's age to die of blunt force trauma while alone in a room. There is also a gap in security video footage for the hours after Lesin was last seen alive. The police report eventually released to the public has been heavily redacted.

Above all, there is a long history of high-profile Russians turning up dead or seriously ill in foreign countries.

RFE said the documents released by the Office of the Chief Medical Examiner show that Lesin's hyoid bone had been completely fractured. An official, whose name was redacted, is quoted as saying such breaks "are commonly associated with hanging or manual strangulation", but that it was also possible that the bone was damaged during the autopsy.

Lesin had amassed a fortune through a company he set up in the 1990s to sell television advertising. He then spent years as Putin's media czar, helping bring national television under Kremlin control during Putin's rise to power. Later he founded the global news network Russia Today, now known as RT. But he abruptly resigned in December 2014 and was believed by some Moscow-watchers to have fallen out of favour with the Putin government.

Australian Associated Press