One of Russia's leading liberal lawmakers Sergei Yushenkov, seen as a close political ally of billionaire businessman Mr Boris Berezovsky, was shot dead last night ear his home in the outskirts of Moscow.
The attack shook Moscow's political establishment to the core, with Russian President Vladimir Putin - whose policies on Chechnya were the target of Yushenkov's scorn - lamenting the loss of a "brilliant politician".
"A man who considered the defense of democratic freedom and ideals his duty has been killed," Mr Putin said, offering his condolences to Yushenkov's family and friends.
The assassination was one of the highest-profile killings in Russia since the 1998 shooting of pro-reform crusader Galina Storovoytova in her apartment's stairwell in the country's second city Saint Petersburg.
Mr Yushenkov (52) served as an independent deputy in the current State Duma lower house of parliament but was originally elected as a member of the Union of Rightist Forces (SPS) liberal bloc led by Mr Boris Nemtsov.
AFP