The government’s lead lawyer in the prosecution of Texas financier R. Allen Stanford is taking early retirement as the Justice Department’s Fraud Section prepares to undergo big changes under new leadership in the Criminal Division, several sources with knowledge of the decision said. The decision comes as the Fraud Section chief prepares to leave for work in private practice.

Current and former Justice lawyers say there is tension in the Fraud Section as the Justice Department continues its search for a section chief, a premier post in the department. Assistant Attorney General Lanny Breuer, the head of the Criminal Division, has put a renewed focus on the section and its work prosecuting fraud on a number of fronts — including in the health care, securities and mortgage arenas.