A House committee investigating Speaker Michael Madigan is receiving guidance from the top federal prosecutor overseeing the criminal investigation into the Speaker. A letter from U.S. Attorney John Lausch delivered yesterday to the Special Investigative Committee outlines parameters for witness testimony. Lausch’s letter said witnesses are not allowed to reveal whether or not they have shared the information they testify to in hearings with federal investigators. They are also not allowed to reveal what federal investigators may have shared with them. The letter does not prohibit witnesses from repeating the facts of their testimony or their recollection of events.