Murder mystery: The death of former Putin aide Mikhail Lesin in 2015 was officially ruled an accident last year, but some FBI agents insist he was beaten to death

A former media adviser to Russian President Vladimir Putin who was found dead in a Washington, DC, hotel in 2015, was scheduled to meet with Department of Justice officials the following day, it was revealed by federal officials Friday.

A months-long investigation concluded last year that Mikhail Lesin, 57, a Russian media executive and one-time Kremlin Putin aide known as The Bulldozer, died as a result of blunt-force trauma to the head, neck and torso caused by multiple falls resulting from binge drinking.

A federal prosecutor announced in October 2016 that Lesin's death was ruled an accident and the case was closed.

But according to two FBI agents speaking to BuzzFeed News on a condition of anonymity, along with another agent and a US intelligence officer, the former Kremlin adviser was beaten to death, allegedly with a baseball bat, after having a falling-out with Putin, and his murder on US soil was then allegedly covered up.

One of the two agents, who were not directly involved with the investigation but learned of its details from co-workers who worked on the case, told the news site of Lesin’s death: 'What I can tell you is that there isn’t a single person inside the bureau who believes this guy got drunk, fell down, and died. Everyone thinks he was whacked and that Putin or the Kremlin were behind it.'

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Mass media minister: Lesin (right) served as Putin's press minister from 1999 to 2004. In the photo above, the two are pictured during a meeting in August 2002

On November 5, 2015, Lesin's battered body was found inside his room at The Dupont Circle Hotel in Washington, just hours before he was set to meet with federal officials

BuzzFeed News also reported, citing unnamed sources within the government, that the Department of Justice had invited Lesin to Washington for an interview and footed the bill for his hotel room, where he ultimately met his grisly end on November 5, 2015.

Federal officials were hoping to learn from Lesin about the operations of the state-run English-language Russia Today TV network, better known as RT, which the Kremlin aide had launched while he was still in Putin's good graces.

Lesin served as Putin's press minister from 1999 to 2004. He was named head of Russia's state-controlled Gazprom-Media in 2013 but resigned the following year and moved to Los Angeles.

In 2014, US Senator Roger Wicker asked the Department of Justice to investigate Lesin for violating the Foreign Corrupt Practices Act. Wicker, a Republican, questioned how Lesin was able to purchase $28million worth of property in Los Angeles after he stopped working for the Russian government.

Five sources told BuzzFeed News that it was Wicker's call for an investigation into Lesin's financial dealings that prompted Putin to force him out of Gazprom.

Fearful for his safety and for the safety of his family, Lesin allegedly contacted the FBI and offered to cooperate

Defector: Lesin, pictured in a meeting with Putin in 2000, was named head of Russia's state-controlled Gazprom-Media in 2013 but resigned the following year and moved to Los Angeles

While Lesin's death sparked rumors of foul play at the time, law enforcement officials said last year the Justice Department had no open investigation of the case.

On the night he died, Lesin was scheduled to attend a Washington gala honoring Russian billionaire and philanthropist Pyotr Aven, according to Radio Free Europe. But he never showed up. He also never made it to the interview with the feds the next morning.

According to a statement issued by Washington's Metropolitan Police Department and the US Attorney's Office for the District of Columbia last fall, Lesin died partly from 'acute ethanol intoxication' caused by excessive drinking.

The FBI and the DOJ have not commented on the newly made bombshells claims, and the DC medical examiner's office said it cannot release Lesin's autopsy results.

A spokesperson for the Metropolitan Police told DailyMail.com in an email message Friday: 'After following up with our homicide team, we have no evidence to suggest this death involved foul play. However, we will certainly reinvestigate should additional evidence be brought to light.'

In an effort to shed light on the circumstances of Lesin's death, BuzzFeed has filed a lawsuit to try and compel the US government to release the FBI investigation file containing evidence in the case.

Meanwhile, Mike Eckel, senior correspondent for Radio Free Europe/Radio Liberty, sued the the Office of the Chief Medical Examiner accusing it of withholding Lesin's autopsy report, which the journalist had requested through the Freedom of Information Act in January, reported Courthouse News Service.

It also emerged on Monday that a Los Angeles mansion owned by a company tied to Lesin went up for sale last week, with an asking price of $23million.

Defector's digs: This Los Angeles mansion owned by a company tied to Lesin went up for sale last week, with an asking price of $23million

The 13,056-square-foot home, located in Brentwood, is owned by an entity registered to Lesin's son, a Hollywood producer

Living in style: The high-end property features seven bedrooms, 11 bathrooms, a massive swimming pool, a dry sauna and a wine cellar

According to the real estate news site The Real Deal, the sprawling 13,056-square-foot home, located in the trendy neighborhood of Brentwood, is owned by an entity registered to Lesin's son, Hollywood producer Anton Lessine.

The palatial property features seven bedrooms, 11 bathrooms, a massive swimming pool, a dry sauna and a wine cellar.

Lessine's business entity, Dastel Holdings, also owned a second property that his late father was said to have purchased after his flight from Russia, a 13,500-square-foot mansion in Beverly Hills that has been on the market since January, with the price tag of $28million.

Lesin's death isn't the first to draw questions about Putin-backed assassinations. The same issues were raised when ex-KGB agent Alexander Litvinenko was poisoned in London with the radioactive element polonium-210 that was slipped into his tea in 2006.

Denis Voronenkov, 45, an exiled lawmaker who fled Russia to Ukraine in October, was gunned down on a city street in Kiev in March 2017.

He was killed four years to the day after another fierce Putin critic, whistleblowing Russian banker Boris Berezovsky, was found dead in unexplained circumstances while on a jog in Britain.