91福利社

As part of The Big Stories: 2015. Alexander Litvinenko, a former Russian spy, was poisoned in a London hotel in November 2006. He drank tea laced with radioactive Polonium, and died three weeks later. It was designed to be the perfect murder, and the cause of death almost went undiscovered. So who killed him and why? For Our World, Richard Watson investigates the polonium trail and reveals how it leads to President Putin's door.