A veteran federal prosecutor recruited onto special counsel Robert Mueller’s team is known for a skill that may come in handy in the investigation of potential ties between Russia and U.S. President Donald Trump’s 2016 campaign team: persuading witnesses to turn on friends, colleagues and superiors.

Andrew Weissmann, who headed the U.S. Justice Department’s criminal fraud section before joining Mueller’s team last month, is best known for two assignments – the investigation of now-defunct energy company Enron and organized crime cases in Brooklyn, New York – that depended heavily on gaining witness cooperation.