Back in the 1990s, Goodfellas jokes were popular among journalists working in Russia.

And for good reason. Brazen public assassinations were common and contract hits were a popular method of resolving political and business disputes. Martin Scorsese's popular 1990 gangster flick seemed an apt metaphor.

But here's the thing. If Boris Yeltsin's Russia was indeed a mafia masquerading as a country, it was a mafia run by a weak, feeble, and often inebriated godfather. And this gave Yeltsin's underbosses a lot of leeway, which they used with impunity.

When Putin came to power, he pulled off the functional equivalent of uniting the proverbial five families.

The mafia metaphor was still apt, but it was now a mafia with a strong godfather and pliant, loyal underbosses. And one of the prime commandments was: Thou shalt not kill other members of the elite -- even those in opposition. At least not without permission.

"Moscow's unspoken rules assumed that once you made it to the very small population of the ruling 'flock,' then despite further developments, even if you go into opposition, your life will be spared," Ivan Yakovina, a former political correspondent for Lenta.ru, wrote in the Ukrainian newspaper Novoye Vremya.

The assassination of Boris Nemtsov has changed all that.

"The killing of a representative of the contemporary Russian ‘nobility,’ a former deputy prime minister who was close to Boris Yeltsin and who was personally acquainted with many world leaders, is a signal to all representatives of this class," Yakovina added.

But what kind of signal is it?

Is it a sign that Putin himself is tearing up this rule and has decided that it is now open season on the opposition? Or is it an indication that Putin's control over his underbosses is slipping?

If the former is the case, the most plausible motive is that by assassinating somebody as high-profile as Nemtsov, it sends a message to the opposition -- to Aleksei Navalny, to Ilya Yashin, and others -- that anybody can get whacked anytime, anywhere. The motive is to instill terror.

"The fear needs to be turned up. If fabricated criminal cases don't instill the desired degree of fear, you must use violence. Otherwise, nobody will believe you are so tough," Navalny wrote on his blog on March 3.

Going Rogue?

And if Putin is losing control of his underbosses, then who exactly is going rogue?

At least one opposition figure is pointing the finger at Chechen leader Ramzan Kadyrov.

"I have no doubt that Ramzan Kadyrov directly ordered the killing of Boris Nemtsov," Konstantin Borovoi said in a recent interview.

Borovoi argued that Kadyrov is trying to strengthen his position as a national politician and is seeking to pressure Putin into giving him a high post in Moscow. And with so many armed men loyal to him, and with many of these loyal armed men fighting in Ukraine, Kadyrov knows he can get away with murder -- literally.

Kadyrov, Borovoi argued, has "put Putin in a hopeless situation. The Russian president can neither punish nor remove him because Chechnya is so difficult to control."

The arrest of five suspects in the Nemtsov assassination -- all of whom hail from the North Caucasus and at least three of whom are Chechen -- has only served to increase the suspicion.

Writing on his Instagram account on March 8, Kadyrov called the chief suspect, Zaur Dadayev, "a true Russian patriot" and a pious Muslim who was shocked by cartoons of the Prophet Muhammad in the French satirical magazine Charlie Hebdo.

It is also worth noting that Dadayev was a member of Battalion Sever, a spetsnaz unit formed by Kadyrov in 2006.

The battalion was commanded by Adam Delimkhanov, Kadyrov's cousin and close associate. Delimkhanov is wanted by Interpol for allegedly ordering the assassination of Kadyrov rival Sulim Yamadayev in Dubai in 2009.

Longtime Enemies

Moreover, Kadyrov and Nemtsov have a long history of open animosity.

Back in 2011, Kadyrov called for Nemtsov to be imprisoned for his role in organizing anti-Kremlin protests. Nemtsov responded by calling Kadyrov "a psychologically very sick man."

In November, Nemtsov called on law enforcement to investigate the infiltration of Chechen fighters into Ukraine.

In January, Nemtsov fiercely criticized Kadyrov on social media after the Chechen leader appeared to threaten former oil tycoon Mikhail Khodorkovsky and Ekho Moskvy editor in chief Aleksei Venediktov.

Kadyrov called Khodorkovsky his "personal enemy" for urging the media to reprint Charlie Hebdo caricatures of the Prophet Mohammed to show solidarity. He also said Venediktov "would be called to account" for running a poll asking whether the media should publish the images.

"With his threats against Venediktov, Kadyrov crudely violates Article 144 of the Criminal Code of Russia: infringing on journalists' activities. Under that charge, Ramzan faces two years behind bars," Nemtsov wrote on Facebook on January 9.

"If I were in Venediktov's shoes," Nemtsov wrote, "I would file a report to [Investigative Committee chief] Aleksandr Bastrykin. Everybody is already sick and tired of Ramzan's threats, but he is certain that Putin will not let anyone touch him, so he is growing increasingly brazen every day."

And less than a week before Nemtsov was assassinated, Kadyrov sent a detachment of toughs to a Kremlin-organized anti-Maidan rally in Moscow. They carried signs reading: "Putin and Kadyrov will prevent Maidan in Russia," alongside photographs of Nemtsov.

The news portal gordonua.com has even posed the question: Are Putin and Kadyrov arguing over the Nemtsov killing?

If they are, they're not doing so publicly. On March 9, Putin honored Kadyrov by granting him Russia's highest state medal.

It looks like those old Goodfellas jokes might make a comeback.

-- Brian Whitmore