The Kremlin's version of the murder of President Vladimir Putin's long-time opponent, Boris Nemtsov, has now coalesced. The main suspect is a Chechen who apparently decided to punish Nemtsov for his defense of the cartoons of the prophet Muhammad published in the French weekly Charlie Hebdo.

But this story has obvious weaknesses -- beginning with the fact that Nemtsov wasn't an anti-Islam radical. If anything, the official narrative about the assassination makes the involvement of the Kremlin and its allies in Chechnya seem more, not less, likely.

Over the weekend, five men were detained on suspicion of organizing and carrying out Nemtsov's murder. All of them are natives of Chechnya, the formerly separatist region in the Russian North Caucasus that is now run like a personal fiefdom by Ramzan Kadyrov, the former separatist field commander who switched sides in 1999 and pledged loyalty to Putin. One of the five, Zaur Dadaev, admitted having played a key role in the assassination.

Under Putin, Russian prosecutors have often drawn a "Chechen trail" in high-profile murder cases: the government has found it convenient to pin crimes on the residents of the country's most restive region. Since Chechnya's wars of secession in the 1990s and 2000s, in which thousands of Russian soldiers lost their lives, Chechens have been highly unpopular in Russia.

In 2006, I was called as a witness in the trial of three Chechen men for the 2004 murder of Paul Khlebnikov, editor of the Russian version of Forbes magazine, where I was publisher at the time of his death. The prosecutor maintained the men had been sent by a retired Chechen field commander about whom Khlebnikov had written an unflattering book. Since the book had been published in 2003 and Khlebnikov never took any security precautions in the interim, I said I found the connection implausible. The jury later acquitted the three men.

Chechens were convicted for organizing the 2006 killing of journalist Anna Politkovskaya, whose coverage of Chechnya was controversial but hardly more so than that of many other journalists. I still don't understand what motive they could have had.

David Fuller's view

It is crude but brutally effective.  Any influential Russian who is critical of Putin now meets an untimely end.  Putin is unstable and weakened, but still utterly ruthless and the biggest threat to Europe.