KEY POINTS:
ROME - In an exotic cast of characters in the Alexander Litvinenko saga, nobody is more mysterious than Mario Scaramella, the self-styled Italian "professor" who lunched with the Russian defector on the day he was poisoned.
It was at the Itsu sushi bar in Piccadilly, where the two men met at 3pm on November 1, that the highest levels of polonium-210 radiation have been found.
Scaramella says he only drank water, while Litvinenko had miso soup and sushi.
Traces of the radioactive substance have also been found in the Millennium Hotel in Grosvenor Square, where the defector had tea with Russian associates later in the day.
And Scaramella himself has now tested positive for the deadly isotope and is being treated at University College Hospital, where Litvinenko died.
Scaramella is not said to be in danger, but somehow he came into contact with the substance.
Litvinenko accused Scaramella of poisoning him from the day he first fell ill to the day he died.
Speaking of the Itsu meeting, Litvinenko said: "Mario didn't want anything, he gave me the email printouts ... I said to myself, he could have sent these emails by computer. But instead he wanted to come and give them to me in person. Why, and why in such a hurry? He was very nervous."
British police have said they do not consider Scaramella a suspect. He flew to London again last week to meet detectives voluntarily, and the bodyguards with him at University College Hospital are there for his protection.
But while Scaramella's problems in Britain may be mostly medical, in Italy last week he found himself at the centre of a criminal investigation.
The accusations date from the five years when he was a consultant to the Mitrokhin Commission, an Italian parliamentary body set up in 2001 on the orders of the then Prime Minister, Silvio Berlusconi, to investigate the activities of Soviet and post-Soviet spies in Italy.
Scaramella claims to be many things, including a professor at Naples University, an honorary magistrate, and consultant to something called the Environmental Crime Protection Programme. But Naples University has not heard of him. The ECPP has no fixed office. The post of magistrate is non-paying.
The only job he has had in recent years over which there is no doubt is with the Mitrokhin Commission. Yet it is this job, which finished before Italy's general election in April, that has now landed him in hot water.
On the orders of the public prosecutor of Naples, Scaramella's phone was tapped. Last week Italian papers published what were reported to be transcripts of conversations between him and the president of the Mitrokhin Commission, Senator Paolo Guzzanti, a member of Berlusconi's Forza Italia Party.
The transcripts allegedly show the two men discussing how Scaramella is to acquire strong enough evidence from Moscow to label Romano Prodi, then the leader of Italy's centre-left Opposition, now Prime Minister, a tool of the Russians. Other members of the Prodi Government were also said to have been targeted, including the head of the Green Party, Alfonso Scanio, who is now Environment Minister.
"We can't go so far as to say Prodiis a KGB agent," Scaramella allegedly says at one point. "But we can saythat the Russians consider Prodi a friend ... "
Guzzanti explodes. "Friend doesn't mean a f***ing thing!" he roars. "Are you taking me for a c**t?"
Lawyers for Scaramella and Guzzanti have protested at the bugging, but have not questioned the authenticity of the transcripts.
Yesterday Oleg Gordievsky, the most senior Russian agent to defect to Britain, said Scaramella's main source for allegations against Prodi was none other than Litvinenko.
Gordievsky agreed with associates of Litvinenko who accused the Kremlin of murdering him.
"Since July Russia has had a law permitting the FSB to kill people abroad that it doesn't like," he said. "They killed a British citizen on British soil, and they are smearing other people, including me."
Whitehall is playing down any suggestion that the contamination of Scaramella makes him a likely suspect.
"It is unlikely for a major suspect to return to a crime scene and even more unlikely for them to voluntarily give police a debrief," one source said. "This is being treated as a suspicious event, not as a murder inquiry."
THE ITALIAN CONNECTION
Some of Italy's leading figures have crossed paths with mystery man Mario Scaramella.
Silvio Berlusconi
Set up the Mitrokhin Commission, which hired Scaramella as a consultant. The commission has been called a crude attempt to smear Berlusconi's opponents as communists.
Romano Prodi
Now Prime Minister. Said to be the principal target of attempts to link Italian politicians with the KGB. Alexander Litvinenko was reportedly among his accusers.
Paolo Guzzanti
Senator from Berlusconi's Forza Italia party and head of the Mitrokhin Commission. Phone transcripts allegedly show him using obscenities as he tells Scaramella to find dirt on Prodi.
Alfonso Scanio
Now Environment Minister and another alleged target of political smear campaign.
- INDEPENDENT