On December 1, 1934, a killing took place that would set the stage for one of the blackest chapters in Soviet history.

The victim was Sergei Kirov, the popular head of the Leningrad Communist Party and one of the few men who could stand toe-to-toe with the increasingly powerful Soviet leader, Josef Stalin.

Stalin was never officially tied to the crime. But he used the murder as a pretext to unleash the Great Terror, eliminating thousands of political opponents by blaming them, directly or tangentially, for Kirov's death.

Aleksandr Orlov, a member of the Soviet secret police who claimed responsibility for organizing Kirov's death, wrote, "Stalin decided to arrange for the assassination of Kirov and to lay the crime at the door of the former leaders of the opposition and thus with one blow do away with Lenin's former comrades."

Eighty years later, Russia-watchers see eerie parallels between Kirov's death and the January 27 murder of opposition leader Boris Nemtsov. Like Kirov, he was charismatic and handsome. Also like Kirov, he was seen by some as a more palatable alternative to the person in power -- in Nemtsov's case, Vladimir Putin.

Observers were quick to notice the echo of Stalin's words and deeds in Putin's reaction to Nemtsov's death. Putin, too, has decried the killing as a provocation and assumed direct control of the investigation.

Some are now wondering if Nemtsov's murder will be followed by another Great Terror -- a period when the Kremlin's remaining detractors will be systematically neutralized.

"The question now becomes whether Kremlin leaders imagine that they can take the country down a similar path of isolation and ultimate destruction," writes Russia scholar Karen Dawisha in an opinion piece for CNN.com. "Or more likely, is the Kremlin thinking at all, or just allowing the terrible logic of this system they have created to unfold?"

So far, the Kremlin has cited a various range of potential culprits in Nemtsov's murder, nearly all of them "outsiders" -- the United States, Ukrainian nationalists, Islamist extremists.

Similarly, Viktor Kravchenko, a Soviet-era dissident, noted that "the first accounts of Kirov's death said that the assassin had acted as a tool of dastardly foreigners -- Estonian, Polish, German, and finally British. Then came a series of official reports vaguely linking [the gunman] with present and past followers of...dissident old Bolsheviks."