Former spy Alexander Litvinenko counted some of the fiercest critics of the Kremlin among his friends — and reportedly even asked to be buried on Chechen soil.

But how did a former KGB agent turned opponent of President Vladimir Putin come to sympathize with a separatist cause that has killed so many Russians — including some of his own former fellow agents? And did his attachment to the Chechens have anything to do with his death?

"He was really a guy [with a] mission," his friend Andrei Nekrasov said, adding Litvinenko was the "odd man out" in their circle of intelligentsia and human rights defenders in London — a robust man of action in a room full of academics.

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Litvinenko had served as an agent in Chechnya and knew the work of security services there well. He used that knowledge once he sough asylum in Britain in 2000, forging a friendship with Chechen rebel envoy Akhmed Zakayev.

At the time he was poisoned with the radioactive substance, polonium 210, Litvinenko was reportedly investigating the October murder of Russian journalist Anna Politkovskaya, a Kremlin critic known for her hard-hitting work on Chechnya.

His experiences — both in Chechnya and after — made him sympathetic to the cause, said Vladimir Bukovsky, Litvinenko's friend and a critic of Putin. The ex-spy was so moved that his dying wish was that his corpse be moved to Chechnya — when peace was at hand.

"On his deathbed, he asked to be buried when the war is over in Chechen soil," Bukovsky said after a memorial service at a London mosque. "He was a fierce defender of Chechnya and critic of the Kremlin."

Litvinenko was well-known for his book on Chechnya, a mostly Muslim oil-producing region in southern Russia where two wars have been fought in the past 12 years between the Russian military and separatist rebels increasingly espousing extremist Islamic ideology.

He claimed a series of apartment house blasts in 1999 that killed 300 people and which the government blamed on Chechen rebels was actually the work of the Kremlin itself. Russia soon invaded the Connecticut-sized area, using the attacks to stir up support for the war.

"He pointed out even before the explosions there was outrageous corruption," Nekrasov said of the Russian secret services. "He had this bent, now he was in England, he talked nonstop. He was obsessed with a desire to let the world know."

Reports that the one-time agent had converted to Islam as he lay dying in a London hospital set off further search for an explanation about what motivated him. The immense suffering of Muslims in Chechnya preyed on his conscience, acquaintances say — and some observers suggest conversion may have been an act of moral redress.

"For Litvinenko, his conversion meant that he associated his struggle for justice with the struggle of the Islamic communities worldwide and in Russia in particular," said Geidar Dzhemal, the head of Islamic Committee of Russia, the leading Islamic advocacy group in Russia.

"Litvinenko must have felt that he shared responsibility for the actions toward Muslims in Russia over the past decade, and he apparently was seeking atonement for the feeling of guilt he had."

Supporters and others say the most compelling sign of support of Chechnya was his apparent conversion — but even that was fraught with controversy. One friend, who spoke to The Associated Press on condition of anonymity because of the sensitivity of the matter, said the family wanted to give him a non-denominational funeral fearing "the inevitable attempt by Litvinenko's enemies to portray him as an associate of Islamist terrorists."

"Clearly, that was a deliberate political action, not an emotional outburst," Dzhemal said. "Litvinenko's conversion wasn't only a spiritual act, it had political importance as well. For Litvinenko, that meant casting a challenge to both the Russian regime and the United States, since Russia and the United States both have been at the forefront of action against the Islamic world."

But as with all things touched by Litvinenko, this, too, is imbued with controversy.

One family friend, Alexander Goldfarb, confirmed an imam had visited him in the hospital, "when he was heavily sedated and on the verge of death." He said he did not know whether his friend had converted.

The conversion was confirmed by Chechen rebel envoy Zakayev, who lives in London and visited Litvinenko in hospital. He said an imam had read Koranic verses over the former spy the day before he died.

The controversy — like his deathbed accusation that Putin was behind his murder — was typical of Litvinenko. Nekrasov said his friend always knew he faced powerful forces — and that he would only be taken seriously after he died.

"He was certainly larger than life," Nekrasov said. "There's a feeling of the quasi-religious dimension about [his death]."

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