Unearthing World War II mass graves and the Boston bombing

Max Pearson presents a collection of this week's Witness History and Sporting Witness episodes from the BBC World Service.We hear about the unearthing of a mass grave in Sernyky, Ukraine, in 1990, and when the Boston Marathon was the target of a terror attack in 2013.This programme contains distressing details.Contributors: James Bulgin - head of public history at the Imperial War Museum in Britain. Richard Wright - archaeologist. Jonathan Dimbleby - broadcaster. Edward Deveau - Watertown Chief of Police. Charles Barnett - managing director of Aintree Racecourse. Gary Anderson - designer.(Photo: David L. Ryan/The Boston Globe. Credit: Getty Images)