The First Assassination of the 21st Century

His death began on November 1, 2006, when he met FSB-agents-turned-businessmen Dmitry Kovtun, Andrei Lugovoi and, possibly, Vyacheslav Sokolenko for tea at London's Millennium Hotel. Later that night, he complained of vomiting, diarrhea and fatigue. He checked into Barnet General Hospital in north London on November 3, but doctors couldn't find anything wrong. After exhausting the possibilities, and with Litvinenko's condition deteriorating, they transferred him to UCH on November 17.

Litvinenko's condition became progressively worse. Pictures of the former spy in his hospital bed show him looking paler than the crisp white walls in the UCH critical-care unit. On November 22, he was intubated and placed on mechanical ventilation. One by one, his vital organs-liver, kidneys, spleen-began to fail. His immune system collapsed as his white-blood-cell count plummeted. And still, doctors did not know what was killing him. "We tried to examine his bone marrow, but it was so flat we couldn't get a sample," Bellingan says. "Something had poisoned all his dividing cells, but it wasn't clear which of many possible agents was involved."

Geiger counters failed to pick up any telltale gamma radiation-the easiest kind to detect-and radioactive thallium poisoning, an early hypothesis, had already been ruled out. "Once gamma was eliminated," Bellingan says, "we were looking at all comers. But the list of possible agents was very, very long." Litvinenko's case had distinguished itself as something new, something more complicated than the British medical establishment could handle. To pinpoint the poison, a sample of Litvinenko's urine went to Britain's Atomic Weapons Establishment (AWE). Researchers there detected signs of alpha radiation.

One of the strongest emitters of alpha radiation is an isotope called polonium-210, generally manufactured for industrial use in anti-static devices. The isotope quickly became the focus of the AWE investigation, but it was too late to do the patient any good. Back at UCH, Litvinenko was fading fast. "His heart was getting weaker and weaker," says Jim Down, the

intensive-care consultant on duty the day Litvinenko died. "His blood pressure dropped inexorably to nothing." The AWE confirmed the polonium diagnosis at about 6 p.m. on November 23, but the news took several hours to reach the hospital. Before it did, at 9:21 p.m., the patient's heart gave out. He never knew the name of his poison.

Internal Decay

Nuclear physicists call polonium "the Terminator"-not because of its efficacy as a poison but because it's the final element created in the process known as slow neutron capture. As an element, polonium occurs naturally in the Earth's crust as a by-product of the decay of uranium-238, and it accounts for about 1 percent of the total annual dose humans get from normal background radiation. In appearance, it resembles a silvery-gray dust-that is, if you can get enough of the stuff together to actually be able to see it. (Litvinenko received an amount that would have fit on the head of a pin with room to spare.) Polonium-210, created by bombarding bismuth-209 with neutrons inside a nuclear reactor, is hard to find in high concentrations. Only about 100 grams are produced every year, most of it in Russia.

Unlike many other radioactive substances, polonium-210 is harmless as long as it remains outside the body. Once inside the body, though, the alpha radiation emitted by the isotope is about 20 times as damaging to cells as the gamma radiation emitted by elements like thallium.

Gamma rays can penetrate steel, concrete, human tissue. Alpha particles can't penetrate even a single sheet of paper, or your epidermis. But when you swallow an alpha emitter-or inhale it, or it enters the bloodstream through an open wound-all molecular hell breaks loose. "It's like firing a missile at a bag of ping-pong balls," says Paddy Regan, a lecturer in nuclear physics at the University of Surrey outside London. "If you coat the inside of a person's gut with alpha particles, the particles will kill every cell they come into contact with."