How Radioactive Poison Became the Assassin’s Weapon of Choice

The mysterious life and brutal death of a Russian dissident.

TUCKED INTO THE Millennium Hotel on London’s Grosvenor Square, the Pine Bar is a place of hush and shadows. Dark wood panelling, leather seats, and black shaded chandeliers cosset those who seek discretion in style. Head barman Norberto Andrade has hidden many celebrities in its recesses during his 27 years of service, including James Bond stars Sean Connery and George Lazenby.

The three Russians who ordered drinks on the chilly afternoon of November 1, 2006 had little of the lethal glamour one might expect of spies. True, two of them were smoking cigars and drinking gin. But the other, a fair-haired man whose slightly angelic face and wide eyes gave him a look of worried alertness, was dressed inelegantly in a khaki t-shirt, jeans, and a denim jacket. He sipped green tea as the smokers, complaining about the small British measures, ordered several rounds of drinks at once. Andrade placed their orders on a tray, but when he reached their table, one of the men obstructed him. The moment had an unforgettably hostile edge to it. He struggled to put the drinks down, finally managing to sit them next to the tea pot.

The men eventually left, and Andrade cleared the table. As he poured the…