Warner Bros. has picked up the film rights to a book on the mysterious death of former KGB agent Alexander Litvinenko; Johnny Depp's Infinitum Nihil will develop the film.

Depp will also possibly star in the big screen version of Sasha's Story: The Life and Death of a Russian Spy, written by New York Times London bureau chief Alan Cowell

In London, the investigation continues into the death of Litvinenko, who was poisoned in late November by polonium-210, Variety reports. Just before his death, he blamed Russian President Vladimir Putin's regime for the murder. Story has become one of the most mysterious and perplexing crimes of the post-Cold War era, triggering an international investigation led by the U.K.'s top counterterrorism officials.

Cowell will document Litvinenko's life and poisoning, as well as address the implications of the case for nuclear proliferation and international terrorism. Initially, authorities thought Litvinenko was poisoned at a sushi restaurant; now they believe he may have been poisoned at another location as well.

No production schedule has been set for Sasha's Story: The Life and Death of a Russian Spy.