An anonymous reader quotes a report from NBC News: The brothers behind this week's Brussels bombings also spied on a top nuclear researcher and hoped to build a so-called "dirty bomb," an expert involved in a probe into ISIS threats told NBC News on Thursday. Khalid and Ibrahim El Bakraoui were responsible for planting a hidden camera outside the Belgian researcher's house, according to Claude Moniquet, a French former intelligence official who was hired to investigate potential plots targeting Europe's nuclear sector. This camera produced more than 10 hours of film showing the comings and goings of senior researcher at a Belgian nuclear center and his family. "The terrorist cell ... naively believed they could use him to penetrate a lab to obtain nuclear material to make a dirty bomb," Moniquet, CEO of the European Strategic Intelligence and Security Center privacy consultancy said. The researcher worked at a center which stored a "significant portion of the world's supply of radioisotopes," according to the Center for Public Integrity, a nonprofit, nonpartisan investigative news organization in Washington, D.C. These isotopes are used in hospitals and factories around the world but can also be used to make a so-called "dirty bomb" -- a device that could spread radioactive material across a wide area.