Man with a life from a spy novel

Former secret agent, political dissident, author, father. Alexander Litvinenko was a man with a life from a spy novel.

As a former lieutenant-colonel in the Russian secret service, he had been looking over his shoulder since moving to north-west London. He knew that, as an outspoken and high-profile critic of President Vladimir Putin, his life and those of his family - a wife and teenage son - were at risk.

The road that led him from Cold War secret serviceman to his death began more than 20 years ago. He became a security agent under the Soviet-era KGB, now known as the FSB, in the late 1980s, after transferring from the Russian military.

A decade later he made a life-changing decision to voice concerns about deep-rooted corruption in the FSB. He publicly exposed an alleged plot to assassinate the tycoon Boris Berezovsky, who now lives in exile in London. It was around this time he fell out with Mr Putin, as head of the FSB, and was sacked, arrested and charged with corruption. Eventually, he was acquitted and fled to the UK where he successfully claimed asylum.

From his position of relative safety, he became a relentless critic of Mr Putin's regime, co-authoring several books. One, Blowing Up Russia: Terror From Within, accused Russian agents of co-ordinating a series of apartment block bombings in 1999 that left more than 300 dead. Moscow blamed the attacks on Chechen rebels and they are believed to have helped swing public opinion behind Russia's war in the breakaway state.

Possibly financially supported by Mr Berezovsky, a billionaire, Mr Litvinenko also appeared in public alongside other opponents of Mr Putin. He denounced the war in Chechnya as a crime, called for Russian troops to be withdrawn and said compensation should be paid to Chechens.

But he remained a patriot. Interviewed four years ago, he said: "I believe Russia will rise again and I will manage to return to the motherland and Moscow."