Mario Scaramella, the Italian who became the first person involved in the Litvinenko poisoning case to be arrested, has been questioned by prosecutors in Rome.
Mr Scaramella is accused of "aggravated and continuous calumny" and of illegal arms trafficking. Prosecutors allege that he invented an elaborate story which featured himself as the victim of an assassination attempt by Ukrainians, to raise his status in Italy as a security expert. The Ukrainians he blamed for the plot are still on trial.
Mr Scaramella has mixed with former eastern bloc secret agents for years, and Italy's Foreign Ministry says that he repeatedly tried and failed to become an agent for the Italian secret services. The charges against him have no direct bearing on the Litvinenko case.
It was at the end of October that Mr Scaramella, 37, called former the FSB agent Alexander Litvinenko, asking for an urgent appointment. The two men met at an Itsu sushi restaurant in Piccadilly, London, on 1 November, and Mr Litvinenko fell ill later the same day. During their meeting, the Italian showed Mr Litvinenko two e-mails which he said proved there was a Russian plot to murder both Mr Litvinenko and himself.
Mr Litvinenko initially blamed Mr Scaramella for poisoning him and the Italian's name figured prominently on Russian and Chechen websites as the guilty party. But for the British police, Scaramella was never a suspect. He was taken to hospital in London with suspected polonium-210 poisoning, but released after a few days when doctors said there was nothing wrong with him.
But the sudden fame he achieved with his Litvinenko connection caused prosecutors in Rome and Naples to look again at an investigation into his affairs they had launched last year.
Mr Scaramella is frequently described as an academic, but his claimed links to universities inside and outside Italy have proved non-existent. The one position on which there is no doubt is that he was retained as an expert consultant to the Mitrokhin Commission of the Italian Parliament.
The commission was set up by Silvio Berlusconi after he became Prime Minister in 2001. It had the ostensible task of looking into interference in Italian affairs by KGB agents. In practice it also dug for - or, as some claim, manufactured - communist-related dirt designed to damage Mr Berlusconi's political opponents.
One of its boldest initiatives was to find, or invent, links between the then opposition leader (now Prime Minister) Romano Prodi and Moscow. Mr Scaramella, thanks to his links to former Russian agents in need of funds, including Mr Litvinenko, was closely involved in this attempt. While working for the Mitrokhin Commission, Mr Scaramella claimed a Ukrainian ex-KGB agent living in Naples, Alexander Talik, had, with three other Ukrainians, cooked up a plot to assassinate him and his political boss on the commission, Paolo Guzzanti, a senator in Mr Berlusconi's Forza Italia party and deputy editor of the Berlusconi-owned daily Il Giornale.
The Ukrainians were arrested and their trial is under way. But Mr Talik claimed that Mr Scaramella had invented the story of the assassination attempt - hence the "calumny" charge. Even more damagingly, they claimed that rocket-propelled grenades sent to the alleged leader of the Ukrainian plot in Italy had in fact been sent by Mr Scaramella himself.
Mr Scaramella denies the charges.His lawyer, Sergio Rastrelli, says he will seek his client's immediate release from prison.