Time Magazine's most recent issue contains a powerful, lengthy indictment of neo-Soviet Russia based on the Litvinenko murder and coverup:

Alexander Litvinenko was buried as he had lived, in a storm. There was rain, hail and a tornado near Highgate Cemetery in north London on the day his lead-lined coffin was lowered into a plot a few yards from that of another dissident who had sought refuge in Britain, Karl Marx. Before the burial, there was a memorial service at a mosque. Several close friends said Litvinenko had converted to Islam a few days before he died, in a kind of atonement for atrocities Russia (and perhaps Litvinenko himself) had committed in Chechnya, although another doubted any conversion had taken place. Litvinenko's widow Marina had requested a nondenominational service at the graveside, but an imam interrupted the proceedings to perform Islamic rites. Litvinenko, a former Moscow anticorruption detective turned furious critic of the Russian government, had a talent for controversy.

The dead man in the Highgate Cemetery started feeling ill on Nov. 1. The London doctors who attended Litvinenko's bedside quickly suspected that some kind of radioactive agent was causing his decline. His hair was falling out, his athlete's body was shriveling, his bone marrow was failing, just as if he had been one of the firemen called to the burning reactor at Chernobyl. But gamma spectrometers found nothing unusual in his blood or urine. As doctors ruled out a slew of increasingly obscure toxins and bugs, the patient's condition worsened. In desperation, the police sent his urine to Britain's Atomic Weapons Establishment, which has equipment beyond the reach of any hospital. There, experts discovered Litvinenko's urine was teeming with radiation--not the gamma rays they had been looking for, which are the usual culprits in radiation poisoning because they can penetrate steel and concrete, but alpha particles, which can be blocked by a single sheet of paper or a layer of human skin. If they get into your bloodstream, though, alpha particles will destroy everything they touch. The Chernobyl occurs inside. This is not a nice way to die.

It was Litvinenko's fate. On Nov. 23, a few hours after the scientists isolated what was causing his body to disintegrate, he succumbed. His was not the quiet, inexplicable demise that a poisoner usually seeks. Instead, those alpha particles, which were shown to come from the rare isotope polonium 210, opened a box of mysteries that have grabbed the world's attention for weeks and turned a gruesome death into the center of a global manhunt and a potential row between Russia and the rest of the world.

The victim had no doubt where the search for his killer would lead: on his deathbed, he said his death had been ordered by Vladimir Putin, the President of Russia. Russian officials have denied that as a malicious provocation. Not surprisingly, Britain is being punctilious about amassing sufficient evidence before it points a finger in any direction. But if some shadowy figures close to the Kremlin turn out to be responsible for Litvinenko's death, it would be the most astonishing indictment of just how ruthless the modern Russian state can be.

All that, as yet, remains unproved. Meanwhile, a slew of whodunit theories are jostling for prominence. Following an autopsy that spurred the police to treat Litvinenko's death as a murder, Scotland Yard antiterrorism officers have been combing sites all over London, while colleagues traveled to Moscow. "This continues to be an extremely complex investigation, and detectives are pursuing many lines of inquiry," said a police spokeswoman. Litvinenko's excruciating and sinister death and the swirl of international politics around it make this a case worthy of John le Carré, but as the police insist, the classic questions of any murder inquiry still apply: Scotland Yard, in short, is looking for motive, means and opportunity.

Who had a motive?

WHY WOULD ANYONE WANT ALEXANDER Litvinenko dead? To answer that question, investigators are having to immerse themselves in the intrigues of postcommunist Russia and their echoes in London, the favored home away from home for Russian exiles, where Litvinenko sought asylum in 2001. (He became a British citizen two months ago.)

Litvinenko had spent the 1990s as an officer in the élite organized crime unit of the Federal Security Service (FSB), which was tasked with penetrating organized-crime gangs in the murky post-Soviet world of big money and official corruption. Like anyone else who touched that cesspit, he had collected some powerful enemies--and at least one ally. That was Boris Berezovsky, one of Russia's first billionaires, who made his money in cars and oil partly by using his excellent connections with Boris Yeltsin to buy state assets for much less than they turned out to be worth. In 1994, as his Mercedes was pulling out of his headquarters, a huge car bomb decapitated Berezovsky's chauffeur but left Berezovsky unharmed. Litvinenko was assigned to the case, and over time the two men became friendly. In 1995 hit men gunned down Vladislav Listyev, a popular TV personality who also ran Berezovsky's ORT-TV network. Officers from a rival organized-crime squad came to Berezovsky's headquarters to arrest him and search for documents. But in the doorway, with his pistol drawn, Litvinenko held off eight of them armed with Kalashnikovs, while Berezovsky furiously phoned allies at the Kremlin. Berezovsky said he and Litvinenko became "like brothers" that night.

Litvinenko claimed to have saved Berezovsky's life a second time. In 1998 he said he had refused an order "to kill the Jew who has stolen half of this country"--by which his superiors meant Berezovsky. As a result, Litvinenko believed, an unsuccessful attempt was made on his life. Those claims were made at a surreal press conference at which Litvinenko appeared with six other disgruntled FSB officers. Some wore ski masks, but Litvinenko, his face uncovered, calmly stated that bosses at the FSB were using the organization "for their private ends to liquidate those who bothered them" and line their own pockets.

Was Litvinenko telling the truth, and if so, was that his sole motivation for grabbing the limelight? Later, two of the officers in the episode claimed the stunt was bought and paid for by Berezovsky, which probably only heightened the rage of the man who had become the FSB's chief--Vladimir Putin. To Putin, a former KGB officer, what Litvinenko had done "was a major act of treason," says former KGB Major General Oleg Kalugin, now an exile in the U.S. after having written about Russia's tilt toward authoritarianism. In his book The Lubyanka Gang, Litvinenko, for his part, said he had gone to Putin before the press conference with proof showing which top FSB officers and high state officials were corrupt. Putin, he wrote, promised to take action--but had Litvinenko tailed instead and hired some of those accused of corruption to work for him. FSB officers arrested Litvinenko on corruption charges in 1999, and he was jailed for eight months. At trial, he was acquitted, then rearrested and jailed for an additional seven months on the same charges (which were quashed), then arrested again. He was eventually released on the condition that he did not leave Moscow.

Litvinenko broke that promise. With Putin having succeeded Yeltsin as President, Litvinenko and his family fled to London in October 2000--shortly after Berezovsky, who was later charged in Russia with fraud, had left for Britain. Litvinenko went to work for the billionaire and lived in a house owned by him. Both agitated against Putin, Berezovsky by financing human-rights and opposition groups and Litvinenko by producing two books furiously critical of the new President. Litvinenko, it is fair to say, didn't like Putin. Last summer he claimed in a letter posted on the Internet that the President was a habitual pedophile. Litvinenko also contended that Putin had been on the take from Mafia groups for years and that to advance his presidential ambitions, he had directed FSB officers to blow up apartment buildings in Moscow in 1999, killing more than 300 people--then pinning the outrage on Chechen rebels. (Putin has vehemently denied any involvement; Russian courts found a group of Chechens guilty of the crimes.) Litvinenko helped make a French film about the apartment bombings and was contributing to a documentary being made in London when he was murdered. This fall Litvinenko had been on the trail of the murderer of Anna Politkovskaya, a persistent critic of Putin's war in Chechnya and human-rights abuses in Russia. Politkovskaya was killed in the doorway of her Moscow apartment in October. Litvinenko was sure the order had come from the Kremlin.

Putin, says Alexei Kondaurov, a former KGB general who is now a maverick Duma deputy, is known for keeping score and for a long memory. So the idea that he would want an infuriating gadfly like Litvinenko to disappear is not beyond reason. But the President's defenders scoff at the idea that he might have been involved in Litvinenko's death. Putin, they say, had no need to get rid of Litvinenko; the exile was an irrelevant crank. Milton Bearden, a former CIA spy in Moscow, as well as other experienced intelligence hands, agrees it would be nuts for Putin--who has had good relations with British Prime Minister Tony Blair--to order an assassination on British soil of a British citizen who was no more than a pest. Says Bearden: "Take a deep breath and take a look at Putin and say, 'Is he stupid or insane?'"

If not Putin, who might want Litvinenko dead? Plenty. Russian Mafia bosses whose networks he was still prying into, for example, or rogue FSB officers who had been paid to rub him out by those who wanted to hurt Berezovsky. Perhaps the culprit was someone who wanted to frame Putin, or a member of the many factions maneuvering to succeed him when his term expires in 2008. One particularly dark theory making the rounds in Moscow was that Litvinenko organized his own death in a bizarre politically motivated suicide. Julia Svetlichnaja, a Russian postgraduate student who met with Litvinenko several times over the past year, last week described an erratic man who said he was going to blackmail at least one famous Russian oligarch with the many secrets he was collecting--or sell them to newspapers. Yegor Gaidar, a Prime Minister in the early 1990s and now an occasional critic of Putin's, came to the President's assistance last week when describing how he had fallen violently ill from an apparent poisoning in Dublin on the day Litvinenko died. Writing in the Financial Times, Gaidar concluded "that some obvious or hidden adversaries of the Russian authorities stand behind the scenes of this event, those who are interested in further radical deterioration of relations between Russia and the West." His implication was that those same or similar adversaries killed Litvinenko.

Who had the means?

THE POLICE ARE TAKING ALL SUCH CLAIMS with a grain of salt--and turning their attention, rather, to the grains of polonium 210 that are at the center of the case. This is no garden-variety poison: polonium needs a nuclear reactor to cook it up and extremely careful handling. At first, the discovery of the element seemed to hang responsibility on the Kremlin. Russia is a big producer of polonium (although its annual output, less than a hundred grams a year, shows just how rare it is). The element is hard to procure. In the U.S., it takes a government license to buy more than minute quantities, and according to the website of United Nuclear, which sells isotopes for use in research labs, it would take about $1 million, 15,000 purchases of the largest unlicensed amount and some fancy lab work to scrape together a lethal dose. (The British Health Protection Agency says the dose that killed Litvinenko was at least 10 times as high as that needed to kill.)

Polonium 210 has some prosaic applications; it is used, for example, in antistatic devices found in photo shops and fabric mills. It would be very difficult, but for less than $1,000, just a few such gizmos could theoretically be disassembled and the contents reworked in a laboratory to produce a lethal dose. To be usable as a poison, Michael Clark, a spokesman for Britain's Health Protection Agency, said last week, the polonium would then have to be mixed in solution, probably with a gelling agent. "If it was some sort of liquid, it could have been--as in James Bond--a little magic capsule," Clark said. All this implies considerable sophistication and resources. A rich, ambitious criminal syndicate might have been able to pull it off; nevertheless, normally it is governments that work on this scale. And obscure poisons have long been a specialty of Russia's secret police, going back to a "toxicological office" that reported to Lenin personally. In the past, the Russians were known to have developed a gun delivering a burst of cyanide gas causing death easy to misidentify as a heart attack, and tiny pellets smeared with the poison ricin, which has no antidote.

In retrospect, it would have been a lot less trouble for someone to push Litvinenko under a bus than to feed him polonium. But it's likely his poisoners did not anticipate the brouhaha his death would cause. "I believe this was a botched operation," says Litvinenko's friend Alexander Goldfarb, who helped him escape from Russia and runs the Berezovsky-funded International Foundation for Civil Liberties in New York City. Without the intervention of Britain's nuclear-bomb lab, the cause of death would have remained shrouded. Boris Zhuykov, chief of the radioisotope laboratory at the Nuclear Research Institute of the Russian Academy of Sciences, says the discovery that polonium was the cause was "an act of scientific heroism. The murderers obviously did not expect that the polonium would be found. They failed because of the excellence of the English gamma spectrometer and the persistence of the research." (Zhuykov says that when he was making these points to Moscow's pro-government NTV network last week, the interview was terminated.)

Who had the opportunity?

SCOTLAND YARD HAS HAD ONE BIG BREAK IN the case: polonium, once released, is like a persistent, invisible dye that marks whatever it touches. Someone who ingests even small amounts will leave an unmistakable trail through sweat and even fingerprints. London's gumshoes have spent the past two weeks following such spores all over town--and beyond.

Litvinenko got sick the evening of Nov. 1, when alpha particles were destroying the lining of his gut. As he began to suspect poison, he focused on two meetings he had earlier that day. One was at a sushi bar in central London with Mario Scaramella, 36, an Italian lawyer and, like Litvinenko, a man drawn to the world of secret information and conspiracy theories. The second meeting was in the Pine Bar of the Millennium Hotel, near the U.S. embassy, with a group of Russian businessmen with whom Litvinenko was apparently hatching business ventures in Britain. "Alexander said both [meetings] were suspicious, and one was probably innocent," says Goldfarb.

For a time, attention focused on Scaramella, but by the end of last week his level of poisoning and other evidence exculpated him of any suspicion. Instead, the trail of polonium was entangling the group of Russians at the Pine Bar. All seven bartenders on duty that day tested positive for the substance, at levels approaching those found in members of Litvinenko's family, implying they had inhaled it soon after its release--possibly from the vapor given off by a drink into which it had been slipped. The Russians who met Litvinenko in the bar included Andrei Lugovoy, a former KGB bodyguard who had met Litvinenko in the 1990s when serving as Berezovsky's security chief at ORT; Dmitry Kovtun, a former Soviet army officer who has lived in Germany for many years and has known Lugovoy since they were 12; and Vyacheslav Sokolenko, a graduate of the same military school as Lugovoy and Kovtun. Sokolenko says he had never met Litvinenko before their brief encounter in London, and that his only interest that day was to attend a soccer match and do some sightseeing. Both Lugovoy and Kovtun have polonium in their bodies, and so far the main focus is on them; both men (and Sokolenko) deny any wrongdoing.

When Lugovoy learned that British authorities were investigating Litvinenko's poisoning, he volunteered for an interview at the British embassy in Moscow. Polonium was later found in the embassy room, and in lots of other places Lugovoy had visited: on planes he had flown between Moscow and London in October; in five rooms at the Sheraton Park Lane hotel, where he had stayed; and in a fourth-floor room at the Millennium Hotel he is said to have used on the day Litvinenko was poisoned. Finding polonium in a hotel Lugovoy had used on a previous trip to London prompted British authorities to wonder if there might have been an earlier, failed murder attempt. A senior British security official thought the sprawl of radioactive markers throughout London and beyond implied an amateur operation, not up to the FSB's usual standard. But another official disagreed. "This is such an extraordinary material to be using as a weapon," he said, "I'm not sure if any standard operating procedures would exist for handling it." Lugovoy's explanation for the traces that seem to track his progress around London was straightforward. "Someone is trying to set me up," he said to the Moskovsky Komsomolets newspaper. "But I can't understand who. Or why."

Nine Scotland Yard detectives were in Moscow last week, trying to talk to Lugovoy. But the interview kept getting postponed for "technical reasons." Cooperation between the Londoners and the Russian authorities has been frosty. Russian prosecutors insisted that they conduct all the interviews, with the British merely suggesting questions. Prosecutor General Yuri Chaika said no Russian citizens would ever be extradited to Britain in connection with the case, while his office suggested that Russia would open its own criminal investigation in London. Lugovoy and Kovtun were said to be in the hospital with radiation poisoning, but there was no independent confirmation of that. After his interview with the British detectives, Kovtun was reported by the usually reliable Interfax news agency to have lapsed into a coma, but his lawyer quickly denied it. Hamburg police found alpha radiation in the apartment of Kovtun's ex-wife and in the home of his ex-mother-in-law, but were not able to say whether the source was polonium 210. For their part, British officials were hoping further tests might let them pinpoint the origins of the polonium, since reactors usually leave signatures in their output. The forensic trail so far points decisively to Russia. But Scotland Yard knows that pursuing Litvinenko's murder back to those who set it in motion, whether official, private or some combination of the two, may never be possible unless someone confesses.

Meanwhile, there is the light--uncomfortably glaring--that the case sheds on modern Russia. Vladimir Ryzhkov, one of the few independent liberals left in the Duma, says, "The point is not whether Putin is responsible for these concrete murders. The point is that he is responsible for having created a system that is ruled by fear and violence." Ryzhkov claims that the armed forces, Interior Ministry, FSB and those who have retired from them to join private security services "are running this country, own its economy and use violence and murder as habitual management techniques." A U.S. businessman in Moscow seconds the argument. "While you in the press are obsessed by Politkovskaya and Litvinenko, you've missed that half a dozen major oil executives and another half-dozen major bankers have been murdered in the last few months." Unlike Litvinenko's sickness, Russia's may not be fatal. But like his, it starts from inside. From his lead-lined coffin, a shadowy figure has illuminated that much.