Mikhail Lesin in 2002. (Sergei Ilntsky/European Pressphoto Agency)

THE DEATH in November in Washington of Mikhail Lesin, a prominent Russian businessman who long survived in the halls of power in Moscow, has left many questions. Mr. Lesin was found dead in his room at the Dupont Circle Hotel, after which family members told the Russian news media he died of a fatal heart attack. Now, four months later, the D.C. Medical Examiner’s Office reports that Mr. Lesin died of blunt force trauma to the head and had bruises on other areas of his body.

Mr. Lesin matured in the twilight of the Soviet Union and was among those who proved fleet-footed enough to capitalize on the opportunities created by the birth of capitalism in the new Russia. Some seized natural resources, others grabbed giant factories. Mr. Lesin’s gamble was on television advertising. When the stolid broadcasters of the Soviet era were replaced by a snazzy independent television news channel, NTV, founded by the oligarch Vladimir Gusinsky, Mr. Lesin’s agency became the exclusive broker for advertising. He made a fortune, navigating business and the corridors of political power. Mr. Lesin’s agency worked to reelect the ailing president, Boris Yeltsin, in 1996. One time, it spliced a taped video message by Yeltsin right before the final vote to conceal the fact the president had just suffered a heart attack.

When President Vladimir Putin rose to power a few years later, Mr. Lesin helped him take control of Russian television and force Mr. Gusinsky out. Mr. Lesin became Russian press minister, played a major role in Mr. Putin’s drive to subjugate the news media, and helped establish Russia Today, a propaganda network. Mr. Lesin surely knew a lot about the obscure workings of Mr. Putin’s Kremlin. He also prospered while in power. According to a letter sent to the Justice Department by Sen. Roger Wicker (R-Miss.), Mr. Lesin’s family owned some $28 million in Los Angeles real estate. In late 2014, Mr. Lesin stepped down from a position at the media conglomerate Gazprom-Media, but did not seem headed for Kremlin ostracism. Nor was he made subject to the U.S. sanctions imposed on so many others in Mr. Putin’s coterie after his invasion of Ukraine.

We don’t know why someone would have assaulted Mr. Lesin, if that’s what happened. But it can’t be forgotten that others who have found themselves on the outs with Mr. Putin have met with violence. Alexander Litvinenko, a former officer of the Federal Security Service, was murdered in London with radioactive polonium. The journalist Anna Politkovskaya was murdered in her apartment elevator. Business owners and others have fled Moscow out of fear.

Why was Mr. Lesin in Washington? What meetings did he hold, or plan? Why was the fact of the “blunt force trauma” kept quiet for so long? Law enforcement authorities should rule out foul play or thoroughly investigate it, and tell the public what they find.