Who killed Alexander Litvinenko?

What started as a horrific killing, became a radioactive trail, and then, nuclear terror in the heart of London.

“Somebody has apparently been deliberately poisoned,” says Doctor Jill Meara, Deputy Director, Health Protection Agency, Radiation Protection.

As holiday season approached, health officials made public the trail of deadly polonium.

Dan McGrory, reporter the Times of London: The police had to say this was an act of nuclear terrorism.

And there was panic.

McGrory: Suddenly London went into a frenzy of polonium poisoning. And so people were suddenly rushing to their doctors; instead of asking for flu jabs and complaining of usual aches and pains and flu—were claiming they were suffering from polonium poisoning.

British Police had never faced anything like this before. The were trying to unravel an international mystery... and get answers for a wife and a son.

Ann Curry, Dateline anchor: You wanna know what happened to your husband.

Marina Litvinenko: Exactly.  Yes.

By following the trail of polonium-210 police had narrowed their search down to four main suspects, an Italian nuclear waste consultant, a Russian tycoon, and a former KGB agent and his business partner, who all met Alexander Litvinenko on the day he was poisoned.

London times reporter Dan McGrory is covering the police investigation.

McGrory: Their original idea was that it happened in the sushi bar…

Police took a hard look at the Italian, Mario Scaramella.

Sure, he been in the sushi restaurant where the polonium was discovered.

But there were reportedly no traces discovered at the table where he and Litvinenko had lunch. So Scaramella was dismissed as a suspect. 

Mario Scaramella: Absolutely not.  He was a friend.

Next, while the polonium trail showed up in the offices of their second suspect, Boris Berezovsky, the radioactive agent wasn’t found anywhere else where the tycoon had been.

As for a motive, Berezovsky said there was no bad blood between him and Litvinenko. What’s more, they were allies against the Kremlin, and Berezovsky apparently had no reason to have Litvinenko murdered.

So police also dismissed him as a suspect.

Berezovsky: I am not involved to his terrible murder.

McGrory: He claimed that it was a dirty tricks campaign by his enemies in the Kremlin, to try and blacken his name.

But what about the other two men - the third and fourth suspects? When police took a long hard look at the movements of Andrei Lugovoi and his partner, they found an astonishing pattern.

McGrory: The police had to go back and check all the places that these men had stayed in, the hotels they’d visited, the bars, the restaurants… and in each of the places they had been, remarkably, they found traces of polonium-210.

Police found polonium on planes Lugovoi and his partner took from Moscow and Germany, in three London hotels where they stayed, in that sushi restaurant where they dined with Litvinenko two weeks before he met with the Italian, Scaramella.

It turned out Lugovoi and his partner had visited the offices of Boris Berezovsky, where the polonium trail led.

And polonium showed up in a seat in the soccer stadium where Lugovoi watched the game.

But police got an off-the-charts reading of polonium-210 in the bar of that upscale hotel where Litvinenko sat with Lugovoi and his partner, drinking tea.

Some 130 people also tested positive for traces of the radioactive substance. So far no one has gotten sick but  nearly all of them had been in the places where Lugovoi and his partner had been.

McGrory: We thought the days of cloak and dagger and Cold War and Russian espionage had gone.

While Scotland Yard has not made any official comments on this case, police and intelligence sources paint a detailed picture of how investigators believe the murder happened: They think Lugovoi and his partner brought the polonium from Moscow to London.  Whether in a liquid or carried as a fine powder, no airport security device could detect the radioactive poison. Then fatal dose was secretly administered and the men returned to Moscow.

Steve Fowler, radiation expert: The amount of polonium-210 that is suspected of being used indicated that the people that did this really intended it to be a lethal dose with no questions asked.

It was in the Millenium Hotel where police  believe the murder was executed.

McGrory: The police are convinced it was in that bar that the poison was given to him - and the most likely explanation is that it was in a pot of tea.

The alleged plot to poison Litvinenko’s tea suggests a scheme of such detailed planning police believe Lugovoi and his partner might be just two members of a bigger assassination squad.

They want to question a possible accomplice, a mysterious figure described as a tall and muscular man with Asian features. Captured on security cameras in a London airport, he apparently traveled on three fake passports and then disappeared.

Lugovoi (through a translator): It’s all a lie. A lie created and spread in the West. I want to stress it’s all a lie.

Lugovoi and his business partner dismiss all the accusations as outrageous allegations. They admit meeting with Litvinenko but say they had nothing to do with polonium-210 or murder in the hotel bar.

McGrory: “If Litvinenko had been poisoned in that bar, then it must have either been somebody posing as a barman or a member of staff.” That was their explanation to the police for what happened in the Millennium Hotel.

In fact, Lugovoi and his partner didn’t try to leave London after Litvinenko was rushed to the hospital; they say they contacted British authorities when they heard he was poisoned; and they say they too are victims of polonium contamination and had to be treated at a Moscow hospital.

Now back in Moscow, they say they are prepared to return to London if they are charged by british prosecutors.

Lugovoi and his partner deny being members of the group of ex-KGB agents called “Dignity and Honor.”

They say someone could have framed them  for Litvinenko’s murder by planting polonium-210 on them.

Joyal: We cannot assume that how this unfolded was the way it was planned or that the people involved actually knew the consequences of the material they were dealing with. 

British authorities apparently have no evidence Lugovoi and his partner had any motive to murder Alexander Litvinenko.

But if the ex-KGB man and his partner were involved, as the polonium trail suggests, police believe the men could have been acting on orders from someone else... someone who could obtain polonium 210.

Joyal: When someone dies from a state-controlled substance, a substance that is manufactured in—in state controlled facilities, where does it come from?

As the trail of polonium leads to Moscow, the biggest question hanging over the murder now is whether anyone in the Kremlin had a hand in it.

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