U.S. Attorney General Eric Holder on Wednesday called for Congress to take steps to help prosecutors build criminal cases against senior Wall Street executives, saying companies often insulated their leaders from responsibility for misconduct. In a speech before New York University School of Law, Holder made some of his most extensive comments yet on improving the prosecution of white-collar crime. He called on Congress to boost rewards for Wall Street whistleblowers and fund more FBI agents with forensic accounting expertise. The Justice Department has faced years of criticism for a dearth of marquee prosecutions against Wall Street executives for conduct that contributed to the 2007-2009 financial crisis. It has reached multibillion-dollar settlements with institutions including JPMorgan Chase & Co, Bank of America Corp and Citigroup Inc, for misrepresenting risks of shoddy mortgage bonds sold before the crisis. But no individuals have faced related charges.