A Spy Thriller, Now a Wife's Endless Pain LONDON - It began as a spy story, rooted in the collapse of the old Cold War and hinting at the start of a new one. Now, it has become a widow's tale. Since November 2006, the commemorations of the death of Alexander V. Litvinenko, a former officer of the Soviet-era K.G.B., have come and gone with metronomic regularity, marked by fading memory and a dawning recognition that one of the most bizarre events in modern criminal history may never be fully explained because the authorities here and in Moscow do not wish it to be. To recap, Mr. Litvinenko, seen as a whistle-blower and an enduring adversary of President Vladimir V. Putin, ingested a rare radioactive isotope, polonium 210, from a poisoned teacup in the Pine Bar of the Millennium Hotel in central London. That was on Nov. 1, 2006, a few weeks after Mr. Litvinenko secured British citizenship. He died an agonizing death on Nov. 23, 2006. British prosecutors accused another former K.G.B. operative of murder, but Moscow, citing constitutional constraints, has refused to extradite him. Since then, almost in parallel, the British authorities have displayed a growing and stubborn insistence that parts of the Litvinenko story relating to the Russian state and the British security services should never be told. Even the question of whether his death could have been prevented may not be considered. The scope of a planned inquest has been restricted by official fiat. An attempt to convene a public inquiry with broader powers of scrutiny has been denied. Through the prism of realpolitik, trade, energy and intelligence-sharing with Russia, and the dictates of international diplomacy in Iran and Syria, all trump disclosure. Quite what the British authorities have gained in return remains as obscure as the secrets the authorities are seeking to protect. In the maneuvering relating to Syria's civil war, Moscow has consistently blocked Western attempts to force President Bashar al-Assad to relinquish power, drawing the West into an arrangement to dismantle Syria's chemical weapons stocks but leaving the conflict to rage on with Mr. Assad in place in Damascus. And, with ironic if unintended echoes of Britain's protection of Mr. Litvinenko when he fled Russia in 2000, Mr. Putin has offered shelter to an American, Edward J. Snowden, who is also seen as a whistle-blower by his supporters. In recent days, though, the focus has narrowed to the bleak image of a widow, framed by the arches of the High Court, sobbing in frustration at the latest in a series of legal setbacks that have blocked her efforts to secure full disclosure about the circumstances of her husband's death. On another note of disclosure, I wrote a book about the Litvinenko case and have maintained an abiding interest. For years, Marina Litvinenko's life with her husband seemed to be set apart from the world he inhabited. In Russia, when they met in 1993, she was a professional ballroom dancer. He was an officer of the post-Soviet F.S.B. domestic security agency. After their flight to London in 2000, she once told me, she settled happily into the world of a homemaker in the uneventful district of Muswell Hill in north London, raising their son Anatoly. On the evening of his fateful encounter at the Millennium Hotel in Grosvenor Square, she had prepared his favorite chicken dish to celebrate the sixth anniversary of their arrival in London. By contrast, her husband spent his days seeking a niche in the half-light between government intelligence agencies and private security companies trawling for information. According to his widow, he was a paid agent of the British Secret Intelligence Service, and had ties to Spanish intelligence. But his death upended everything, casting her into the public eye as the champion of a cause. "It is not just in my interest to get to the truth of this," she said recently. It is in the public interest. It's for everyone in Britain to ask: why? Who did it? At every turn, though, her efforts to secure a full inquiry have been thwarted. The latest obstacle came last week when three high court judges turned down a request to set a formal limit on the potentially ruinous costs she might incur from the fees charged by government lawyers if she loses the next battle in her continuing fight for a full inquiry. Her own legal team is acting pro bono. "What I am doing, I am doing for my husband," she told The Guardian. But if I decide to carry on, there is a huge risk that we will be homeless and will lose everything. I need to take some very serious decisions. Days later, a lawyer acting for her said, she resolved to "continue her fight to uncover the truth about her husband's death, despite mounting adversity." Throughout her time in London, there was, until earlier this year, another figure who played the role of mentor and sponsor. Boris Berezovsky, a former oligarch who made his billions in the freewheeling days after the collapse of the Soviet empire, had been an ally since 1994, when Alexander Litvinenko was assigned to investigate an attempt on his life. But his financial support shrank after he lost a $5.1 billion lawsuit a year ago and told Mrs. Litvinenko he could no longer bankroll her crusade. Mr. Berezovsky was found hanged in as yet unexplained circumstances in March. Still, though, Mrs. Litvinenko believed that the authorities in her adoptive land, with their reputation for justice and fair play, shared her desire for closure. Then came the latest ruling. "Now I feel the British government is only trying to protect itself," she said. I feel I am alone.