Asked about the recent dismantling of a high-profile unit in the U.S. attorney's office in Los Angeles that specialized in public corruption cases, an office spokesman provided what some saw as a curious justification: Eliminating the public integrity and environmental crimes section, spokesman Thom Mrozek said, would actually enhance the effort to prosecute such cases. He explained that the unit's 17 lawyers would be farmed out to other sections in the office and that those types of cases would now be handled by a larger pool of attorneys, instead of by a select few. But in interviews with The Times,...