Coming soon to a cinema near you, the curious case of Alexander Litvinenko

From its cast of spies, presidents and billionaires to its execution with poison, the death of Alexander Litvinenko always sounded like it had come from the script of a Hollywood thriller.

Now Tinseltown is looking to return the favour. Two films about the murder of the former KGB agent in London last year are under development with the involvement of the actors Johnny Depp and John Malkovich.

The film projects are the latest stage in the conversion of Mr Litvinenko's killing, which left 120 people contaminated with the radioactive polonium-210 used to kill the Russian exile, into a commercial enterprise.

It was revealed yesterday that among those writing books on the saga are Mr Litvinenko's wife, Marina, and Alex Goldfarb, a family friend and employee of Boris Berezovsky, the oligarch who was Mr Litvinenko's financial sponsor.

The Hollywood studio Warner Bros is basing its film on a yet-to-be-published book of the saga by Alan Cowell, the London bureau chief of The New York Times.

Charlie Conrad, executive editor of the publisher Doubleday, which is producing Mr Cowell's book, said the poisoning of Mr Litvinenko had an obvious appeal as a book or film. He said: "It reintroduces to the public all the mysteries of the Cold War. It's a great example of the truth being stranger than fiction."

Variety, the showbusiness newspaper, reported that Warner had bought the film rights to Mr Cowell's book to be passed on to Mr Depp's production company, Infinitum Nihil. The deal reserves the right for Mr Depp both to coproduce and star in any subsequent film, which is likely to be made with the British producer Graham King, a front-runner for an Oscar for his latest project, The Departed.

The second film is based on a book coauthored by Mr Litvinenko before his death, Blowing Up Russia, which suggested that the FSB security service - successor to the KGB - killed hundreds of civilians in 1999 by blowing up apartment blocks to re-start the Chechen War. The rights to the book, which infuriated the Kremlin, were bought for a six-figure sum last month by the Beverly Hills-based Braun Entertainment Group. The company is reported to have approached Mr Malkovich about playing Mr Litvinenko.

The bidding activity has also included Mr Litvinenko's family and friends as publishers seek the "definitive" account of the killing. Simon & Schuster confirmed that it has signed a deal with Marina Litvinenko and Mr Goldfarb, who acted as a spokesman for the family after Alexander, known to his friends as Sasha, became seriously ill on 1 November. The publishing house said the book was scheduled to reach book shops in May and would be in the "style of a political thriller".

Ed Victor, the literary agent who sold the book, said: "A lot of people are writing books about Litvinenko at the moment, but none will have the intimacy and emotional connection of this one."

In a separate development, Russia's deputy prosecutor-general stepped up the pressure on the British government to allow detectives from Moscow to conduct an investigation in Britain. Aleksander Zvyagintsev said in a newspaper interview that investigators have handed a 110-page dossier to the Home Office which names more than UK-based 100 witnesses they would like to interview. The Home Office declined to comment on claims in Russian media that it is "stalling" on issuing visas to Russian investigators.