The U.S. Justice Department’s internal watchdog has opened a criminal probe of an FBI agent’s leaks to journalists about an insider trading probe involving a Las Vegas sports gambler and professional golfer Phil Mickelson, a prosecutor said on Wednesday. Joan Loughnane, chief counsel for Manhattan U.S. Attorney Preet Bharara, disclosed the probe by the Justice Department’s Office of the Inspector General during a court hearing on the insider trading case against gambler William “Billy” Walters.