Three pathologists conducted the examination at the Royal London Hospital: one from the British Home Office, another working on behalf of the Litvinenko family, and a third as an independent expert.
The autopsy results will be first analyzed by toxicologists before being publicly announced.
Russian security defector Litvinenko, an outspoken critic of President Vladimir Putin's administration and a close associate of exiled oligarch Boris Berezovsky, died in a London hospital with symptoms of radioactive poisoning. British health officials said a large dose of polonium-210, a radioactive, toxic uranium by-product, was found in his body.
Following Litvinenko's death, the Western press circulated a message purporting to be his deathbed note, in which he accused Putin of orchestrating his death, an allegation the president dismissed.
