The Kremlin has a reputation for using the courts to rein in--or bring down--rivals. Witness the demise of Mikhail Khodorkovsky, the former boss of Yukos Oil. So it's no surprise that Mikhail Kasyanov should be the latest target of an investigation. The former Russian prime minister, fired by President Vladimir Putin in February 2004, had only recently stepped out of the political shadows to criticize the government--and possibly position himself as a candidate in Russia's 2008 presidential elections. Is it entirely coincidental that federal prosecutors now accuse him of using his former office to buy a fancy state-owned dacha at a fire-sale price?

On their face, the charges indeed seem suspect. Moscow media report that Putin ordered law-enforcement agencies to go after Kasyanov two months ago. The probe announced last week was instigated by a pro-Kremlin member of Parliament cum investigative journalist, Alexander Khinstein, who on July 3 published an article claiming that Kasyanov used his political office to engineer the purchase of a state-owned country house worth $28 million for the comparatively paltry sum of $1 million. Kasyanov, 47, denied the allegations through his press secretary--who added that the former P.M. was on holiday abroad. Outgoing U.S. Ambassador Alexander Vershbow expressed concern that the accusations were linked to Kasyanov's political ambitions. Opposition activist Leonid Gozman of the Union of Right Forces branded the move as "an attempt to intimidate" Kasyanov, highlighting yet again the Kremlin's determination to crush potential challengers.

Rarely are things so simple in Russian politics, however. Yes, Kasyanov may have spoken out against the government--accusing it, among other things, of squashing democracy and stalling economic reforms. And yes, he's been bandied about as a presidential contender. But what, realistically, would his chances be against a Kremlin-chosen successor to Putin? As for Kasyanov himself, the man once dubbed as Misha 2% (for the take he allegedly garnered on financial transactions flowing through his office) is anything but a political white knight.

More likely, the case is a sign of the Kremlin's growing paranoia. In a recently published book, "Kremlin Rising," Washington Post correspondents Peter Baker and Susan Glasser tell how Kasyanov lost his job. Worried about low turnout in the 2004 election--and what would happen if, under law, Kasyanov became president for a month until a new ballot could be held--Putin simply dismissed him a few weeks before the vote. Once again, it seems, the Kremlin is taking no chances.