Plutonium is an important radioactive heavy metal, used mainly in nuclear weapons and some types of nuclear reactors. It emits alpha particles, a form of ionizing radiation that can damage living ...

The U.S. government's negligent curiosity about radiation poisoning was an overcorrection to its previous negligent ignorance about the subject. Robert Oppenheimer and Gen. Leslie Groves, who ran ...

In 2006, Alexander Litvinenko had tea with two Russian men at the Millennium Hotel, pictured here, in London. Three weeks later, he died of radioactive poisoning. Matt Dunham ...

Prosecutors accused a former KGB agent Tuesday of murder in the radioactive poisoning of fellow ex-operative Alexander Litvinenko and sought his extradition from Russia.

Britain says it will expel four Russian diplomats from their embassy in London because Russia won't hand over the murder suspect in the poisoning of an ex-KGB spy.

Litvinenko, 43, died Nov. 23 in London, three weeks after he became ill following a meeting at a sushi restaurant. Doctors found the rare radioactive substance polonium-210 in his body.