Who killed Litvinenko?

Alexander Litvinenko was a man who could be taught little about the seamy side of modern Russia. A KGB agent for 18 years, he occupied a world where intrigue, betrayal and ruthless trickery were the tools of working life.

But even a man whose job was to fight organised crime and counter subversion in the name of the Kremlin would have been surprised at an event as mired in low chicanery, high drama and cold-blooded cunning as his own passing. The spy novel saga of the life and death of the 43-year-old secret agent turned vehement critic of Vladimir Putin entered its most extraordinary phase yesterday when it was revealed that he died from exposure to a radioactive poison.

Last night, the Government was dealing with a public health alert and diplomatic crisis after traces of polonium 210, a by-product of uranium, were found at Mr Litvinenko's home as well as a sushi restaurant and London hotel he visited on 1 November.

The Health Protection Agency (HPA) confirmed that traces of the heavy metal, which is lethal if ingested in tiny quantities, were found in Mr Litvinenko's urine.

Until he died from heart failure on Thursday night, doctors had failed to pinpoint the cause of symptoms that reduced a man who ran five miles every day to a "ghost" with a crippled immune system and a useless liver. A post-mortem will not be carried out until it is deemed safe for hospital staff to do so.

Scotland Yard, whose anti-terrorist branch is leading the investigation, said it had closed the Itsu sushi restaurant and part of the hotel in Mayfair after HPA experts found traces of the chemical element polonium.

In a sign of the potential damage to relations between London and Moscow, the Foreign Office said it had asked the Russian government to provide " any information" that would help Scotland Yard's investigations. A spokesman said: "We've obviously raised it and it is a serious matter."

It is believed that Mr Litvinenko somehow ingested a small amount of polonium 210 on or around 1 November. Although harmless to the outer skin, the heavy metal, in quantities no larger than a pinch of salt, destroys internal organs by causing severe radiation poisoning.

The HPA described the risk of contamination to others who had come into contact with Mr Litvinenko on 1 November and subsequently as "minimal".

But the agency confirmed it was drawing up lists of staff at the two London hospitals where the Russian, who recently gained British citizenship, was treated and "tens" of staff would have to undergo screening for exposure to radioactivity. Staff at the sushi restaurant would also be assessed, the agency said.

Professor Pat Troop, chief executive of the HPA, said: "What we know is that this man had a high dose of radiation and our responsibility is to say: 'Has that caused a risk to others?'

"For somebody to have this level of radiation they would have to have eaten it, inhaled it or taken it in through a wound. It is not yet clear how this entered his body."

The answers to that question lie in the events of 1 November and Mr Litvinenko's 18-year career in the KGB and its successor, the FSB. It brought Mr Litvinenko into contact or opposition with some of the most powerful figures in Russia during the break-up of the Soviet Union and the emergence of Mr Putin as a political leader admired and feared in equal measure.

It ended after encounters with a set of characters who could have been drawn from a James Bond film, ranging from an Italian academic and KGB expert once targeted by the mafia to a football-mad businessman who once guarded the Russian Prime Minister. But it was Mr Putin whom Mr Litvinenko chose to blame for his demise. Aware that the substance in his body was killing him, the former spy, along with his supporters, had the presence of mind to dictate a statement four days ago in which he made clear who he blamed for his condition.

In a statement released yesterday, Mr Litvinenko wrote: "As I lie here, I can distinctly hear the beating wings of the angel of death. I may be able to give him the slip, but I have to say my legs do not run as fast as I would like."

He continued: "You have shown yourself to be as barbaric and ruthless as your most hostile critics have claimed. You may succeed in silencing one man but the howl of protest from around the world will reverberate, Mr Putin, in your ears for the rest of your life."

The response of the Russian President, attending a European Union summit in Finland, was blunt: "There is no ground for speculation of this kind. A death of a man is always a tragedy and I deplore this and send my condolences to the family."

Last night, legislators in Moscow suggested Mr Litvinenko's death was part of a plot against Russia. "The death of Litvinenko ­ for Russia, for the security services ­ means nothing," Valery Dyatlenko, a former head of the FSB, said on state-run Channel One television, contending that neither the Kremlin nor Russia's intelligence agencies would have had reason to kill him.

Police are now investigating the contacts which Mr Litvinenko made in London as he established a reputation as a strident critic of the Kremlin, in particular its policy in Chechnya.

Known as Sasha to his friends, he had come to Britain in 2000 after turning whistleblower on the FSB, claiming he had been ordered to assassinate the virulently anti-Putin oligarch ­ and his subsequent patron ­ Boris Berezovsky. He was quickly submerged into Berezovsky's circle of influential emigrés.

The exiled agent settled in Muswell Hill, a respectable corner of north London, in a large modern house owned by Mr Berezovsky. Shortly afterwards he was joined by his wife, Marina, 41, and their 12-year-old son, Anatole. Across the road lived Akhmed Zakayev, the foreign minister of the exiled Chechen government.

All this came to an abrupt halt on 1 November. Mr Litivinenko held two meetings on that Wednesday. It was the sixth anniversary of his arrival in Britain as a political refugee, having been an agent in the FSB unit tasked with countering organised crime gangs in the 1990s.

The first, at 10am, was at the Millennium Mayfair Hotel in central London with Sergei Lugovoy, a former KGB bodyguard and businessman who runs a security company in Moscow. Mr Lugovoy said he had been in London to watch a football match between Arsenal and CSKA Moscow. Also at the meeting were two other people unknown to Mr Litvinenko ­ Dmitry Kovtun, the business partner of Mr Lugovoy, and another friend and partner named as Vyacheslav Sokolenko. Friends of Mr Litvinenko insist that he drank tea during the meeting.

Mr Lugovoy, former bodyguard to a Russian Prime Minister, Yegor Gaidar, who claimed to have renewed his 10-year relationship with Mr Litvinenko only recently, said last night that his business contact had taken no food or drink.

He said they had held a "very constructive" meeting, but Mr Litvinenko had cancelled a second breakfast meeting the next day after falling ill. The businessman denied any involvement in the death. He said: "I'm surprised by how hysterically some are trying to tie me to this." By 3pm, Mr Litvinenko had moved from Mayfair to the elegant façades of Piccadilly, where he met Mario Scaramella, another long-standing contact who had called him out of the blue saying he wanted to bring forward a meeting planned for 10 November to discuss important documents. The Italian examining magistrate who, among his many job descriptions, includes the titles of environmental campaigner and law professor, told Mr Litvinenko that he had received a death threat aimed at both of them. They met for 35 minutes in the basement of a branch of Itsu, a sushi restaurant chain. Mr Scaramella said last week that, while he himself drank only water, Mr Litvinenko bought food and drink from a chiller cabinet.

The documents they discussed, seen by The Independent, accused both men of being part of a conspiracy to besmirch the name of the FSB and there was a "necessity to use force" to silence them. The papers also purported to name a retired KGB agent who was responsible for planning the murder of the dissident journalist Anna Politkovskaya at her Moscow apartment in October.

Mr Litvinenko, a friend of the reporter, had been very public ­ perhaps dangerously so ­ about whom he believed to have been responsible for the murder. Thirteen days earlier he had stood up in front of an audience journalists and campaigners at London's Frontline Club and accused Mr Putin of being involved.

The motivation of those who may have somehow slipped polonium 210 into Mr Litvinenko's food or drink remains unknown. Theories abound, from an officially sanctioned "hit" by the FSB against a man seen as a traitor in Moscow, to an attempt to besmirch Mr Putin and his administration by rogue opponents, or a macabre suicide by Mr Litvinenko himself. The last scenario was described by one friend last night as "utter rubbish".

But what happened to the Russian agent following those meetings on 1 November is not in dispute ­ a ghastly slide by a former pentathlete from rude health into a man with the appearance and demeanour of a cancer patient.

Initially, Mr Litvinenko spent 10 days at Barnet Hospital in north London. Staff put his extreme vomiting down to a violent stomach bug before moving him to a cancer ward when his white blood cell count dropped to zero. Poisoning was only investigated when he was transferred to University College London Hospital on 17 November and toxicology tests revealed small traces of thallium, known as the "secret agent's poison" ­ it is odourless, tasteless and lethal in small quantities.

What had thus far been only reported on a single pro-Chechen website suddenly became worldwide news. Alex Goldfarb, the eloquent human rights campaigner who had arranged Mr Litvinenko's escape from Moscow in 2000, emerged as the official spokesman for his friend.

Behind the scenes, the exiled oligarch and arch-critic of Mr Putin, Boris Berezovsky, called in his PR agency, Bell Pottinger, to handle media inquiries. It was Bell Pottinger which distributed what will become the defining image of Alexander Litvinenko ­ a photograph of his shrunken and yellowed features taken in his hospital bed with wires to a bank of medical machines trailing from his chest.

Such pictures of high political drama were a long way from the provincial backwater of Nalchik, the town in the far south of Russian where Mr Litvinenko was born in 1963, the son of a doctor. Described as "bright and principled", a 20-year-old Alexander joined the KGB in 1983 and rose through the ranks to become a lieutenant-colonel in the section dealing with organised crime.

It is understood that he had special responsibility for countering attempts by the Russian mafia to infiltrate the security services. In 1998, he declared his failure at this task. At a press conference he accused the FSB, then headed by Mr Putin, of ordering him to assassinate Mr Berezovsky. In turn charged with corruption by Moscow, Mr Litvinenko fled to London and continued his onslaught with a book, The FSB Blows Up Russia, in which he accused his former employers of murdering 300 people in 1999 by demolishing apartment blocks with explosives and blaming the attacks on Chechen rebels.

A series of further allegations were made, some of which ­ such as the claim that the Kremlin had ordered the Beslan massacre ­ were seen as undermining his credibility.

Amid reports of a tape recording which supposedly implicates senior Kremlin figures in a sex scandal, it is clear that Mr Litvinenko made enough enemies in enough places who could now make it on to the list of suspects for what the Yard was last night calling his "unexplained death".

But, yesterday, it fell to his father, Walter, to summarise a life and death far out of the ordinary. Dressed in a leather jacket and an orange scarf, Mr Litvinenko choked back tears and anger as he spoke to reporters outside University College London Hospital. He said: "My son died yesterday and he was killed by a little, tiny nuclear bomb.

"He faced his last hours with dignity. He was very courageous when he met death and I am proud of my son."

The leading players in an espionage drama

Vladimir Putin

The Russian president was accused by Mr Litvinenko of sanctioning his murder. The Kremlin has rejected the claims, but the death of the former agent will add to the perception that the FSB security service is running an assassination policy.

Mario Scaramella

The Italian academic and KGB expert met Mr Litvinenko at a sushi restaurant on the day he fell ill. There is no suggestion that Mr Scaramella was involved in the poisoning. He said he had met his friend to discuss a death threat aimed at them.

Andrei Lugovoy

The Moscow-based businessman and former KGB bodyguard held a meeting with Mr Litvinenko at a hotel on 1 November. Mr Lugovoy had tea with Mr Litvinenko and two other men. Mr Lugovoy said the meeting had been to discuss business and he had been in London to see a football match.

Boris Berezovsky

The exiled Russian oligarch had become an ally of Mr Litvinenko. Mr Berezovsky, a critic of Mr Putin, is thought to own the house in north London where Mr Litvinenko was living and financed his book, which levelled corruption and murder allegations against the FSB and Kremlin.

Akhmed Zakayev

The former actor and foreign minister of the Chechen government in exile was a visitor to Mr Litvinenko's bedside. The two men were neighbours. He accused the Kremlin of exporting "gangster politics" to London.

Lord Tim Bell

Bell Pottinger Communications, of which Lord Bell is chairman, includes Mr Berezovsky among its clients. The company handled media calls about Mr Litvinenko and arranged for the distribution of photographs taken of him in hospital.

Alex Goldfarb

The biochemist is director of a human rights group set up by Mr Berezovsky in 2000. Mr Goldfarb has put forward the allegation that the Kremlin is responsible for Mr Litvinenko's death.

John Henry

The leading toxicologist claimed that thallium was to blame for Mr Litvinenko's condition. But the hospital said he had made his remarks without seeing test results. The professor said he has withdrawn from the case.

Countdown to tragedy

7 October

Russian journalist Anna Politkovskaya is shot dead in Moscow. Litvinenko begins to investigate her murder.

1 November

Litvinenko meets former KGB officer at Millennium Hotel, London, then meets Italian academic Mario Scaramella at Itsu sushi bar in Leicester Square. Later admitted to Barnet General hospital.

17 November

His condition worsens and he is transferred to University College London Hospital.

19 November

Reports emerge that he has been poisoned with thallium.

20 November

Litvinenko moved to intensive care. Scotland Yard say they are treating it as a suspected deliberate poisoning. Kremlin dismisses allegations of involvement.

22 November

As his condition worsens, doctors rule out thallium and radiation poisoning.

23 November

After suffering a heart-attack overnight, doctors say he is critically ill. Later that night, statement is issued saying he is dead.

24 November

It emerges that radioactive material is found at hotel and restaurant which Litvinenko visited. His family release statement from former spy in which he tells Vladimir Putin "may god forgive you for what you have done".