Check for polonium.

Mr. Dobrovinsky wrote in Russian on his Facebook page: “Just got a call from London. Boris Berezovsky has committed suicide. The man was complex. An act of desperation? Impossible to live poor? A series of blows? I am afraid that no one will know the truth.”

The Thames Valley police in Berkshire, an hour from London, said Saturday that they were investigating the “unexplained” death of a 67-year-old man, apparently Mr. Berezovsky, in Ascot.

The police statement did not name Mr. Berezovsky, but British news reports said an investigation was under way at his home. “Specially trained officers are currently at the scene, including C.B.R.N.-trained officers, who are conducting a number of searches as a precaution,” said a spokeswoman for the Thames Valley police, referring to the force’s chemical, biological, radiological and nuclear team. “This is to enable officers to carry out an investigation into the man’s death. The body of the man is still in the property at this time.”

via Boris A. Berezovsky, a Putin Critic, Dies Near London – NYTimes.com.