A senior Justice Department official recently flagged by a U.S. senator in an FBI whistleblower probe into alleged politicization of prosecutions played a key role in the Lois Lerner IRS scandal a decade ago in which conservative Tea Party groups were improperly targeted for scrutiny, government emails and congressional evidence shows.Richard Pilger, the current chief of the DOJ Elections Crime Branch of the department's Public Integrity Section, engaged in discussions in 2010 and 2013 with Lerner and other IRS officials about ways to pursue criminal prosecutions of conservative nonprofits, the records show.The discussion led the FBI, with Pilger's direct help,...