Those familiar with Russian politics know that Vladimir Putin’s Kremlin has been making a concerted effort of late to whitewash Russian history by issuing a new set of history texts that praise Josef Stalin and the institution of dictatorship in Russia.

It’s perhaps not surprising that Putin, a proud career KGB spy, is taking out his eraser, and likely that he has no intention of stopping at his own term in office. You see, his critics have an embarrassing habit of disappearing.

Less than four months after Putin was named chief of the FSB (successor to the KGB) in 1998, Russia’s leading human rights activist Galina Starovoitova was shot and killed; her murder remains unsolved. No sooner had Putin been named prime minister than a brutal war erupted in Chechnya; Russia has since been repeatedly convicted of state-sponsored murder by the European Court for Human Rights in connection with that conflict.

The war followed close on the heels of the bombing of two apartment buildings in Moscow; hundreds of innocent people were killed, and KGB defector Alexander Litvinenko accused Putin of ordering the bombings in order to blame them on Chechnya and justify his invasion. Litvinenko was murdered in November 2006 with radioactive toxin traced to Russia, and Scotland Yard has blamed the Kremlin (which has refused to extradite the key suspects). Litvinenko was not the first apartment bombing critic to perish: In April 2003 Sergei Yushenkov, a leading opposition politician and chairman of a select committee that had been investigating the bombings, was shot and killed near his apartment. Three months later a key member of the committee, Yuri Shchekochikhin, was fatally poisoned. A few months after that the committee’s lawyer, Mikhail Trepashkin, was arrested and sent to prison for four years.

Then things really started getting ugly. Having been elected president in the wake of the Chechnya war, Putin’s poll numbers fell because the Chechnya conflict became a quagmire. As his reelection campaign cycle began his primary opponent, billionaire Mikhail Khodorkovsky, found himself arrested in October 2003 and sent to prison in Siberia. Soon after Putin’s unsurprising reelection (with no opponent and no debates), Nikolai Girenko, a prominent human rights activist, and Paul Klebnikov, a leading investigative journalist, were both shot and killed. When, a few months later, Ukraine’s president, Viktor Yushchenko, began moving towards NATO membership, he was poisoned with Dioxin (but survived). It was not long before crusading reformer Andrei Kozlov, First Deputy Chairman of Russia’s Central Bank, also lay dead of gunshot wounds.

But, amazingly, the most sensational and horrifying killings were still yet to come: In October 2006 Russia’s leading independent journalist, the valiant Anna Politkovskaya, was shot and killed at her apartment, and the next month Litvinenko too was gone. Both killings remain as mysterious as Starovoitova’s.

When Putin’s handpicked successor, Dmitri Medvedev, entered the election cyle, his chief rival former Mikhail Kasyanov was accused of campaign fraud and stricken from the ballot; leading rights activist Oleg Kozlovsky was illegally drafted into the army and sent into the hinterlands, to be released only after the “vote.”

More recently, a mysterious chain of incidents has occurred. In February 2007 journalist Daniel McGrory and scholar Paul M. Joyal were interviewed by NBC about the Litvinenko killing, and both blamed it on the Kremlin. McGrory died suddenly five days before the broadcast aired, and Joyal was shot near his home five days afterwards.

Which brings us to last month, when two more Kremlin critics made news. In the last two weeks, jet-setting billionaire Leonid Rozhetskin and artist Anna Mikhalchuk (pictured above), both prominent critics of the Putin regime, have mysteriously vanished. Like McGrory and Joyal, the links between these events and the Kremlin are murkier than they are with Politkovskaya, Litvinenko and the others, and yet it’s almost impossible to avoid considering them.

They are frightening. The world has yet to send a really firm message to the Kremlin, despite all this carnage, that political murder will not be tolerated. Russia still sits on the G-8, and has reason to hope for WTO admission. Western leaders are increasingly distant from the Kremlin, but not aggressively critical.

Why shouldn’t the Kremlin think it has gotten away with murder? And why shouldn’t it continue along that path? Of course, there is great irony in Vladimir Putin presenting to the world the image of a powerful, confident ruler and yet apparently feeling the need for so much violence against individual opposition figures. But if Putin believes that its somehow necessary, and hasn’t seen real consequences, why shouldn’t he continue?