Investigations led by a Republican lawyer named Stuart W. Bowen Jr. in Iraq have sent American occupation officials to jail on bribery and conspiracy charges, exposed disastrously poor construction work by well-connected companies like Halliburton and Parsons, and discovered that the military did not properly track hundreds of thousands of weapons it shipped to Iraqi security forces. And tucked away in a huge military authorization bill that President Bush signed two weeks ago is what some of Mr. Bowen's supporters believe is his reward for repeatedly embarrassing the administration: a pink slip. An obscure provision...terminates his federal oversight agency, the Office of the Special Inspector General for Iraq Reconstruction. The clause was inserted by the Republican side of the House Armed Services Committee. It has generated surprise and some outrage among lawmakers who say they had no idea it was in the final legislation. Susan Collins, a Maine Republican who followed the bill closely as chairwoman of the Senate Committee on Homeland Security and Government Affairs, says that she still does not know how the provision made its way into what is called the conference report, which reconciles differences between House and Senate versions of a bill. Neither the House nor the Senate version contained such a termination clause before the conference, all involved agree. Mr. Bowen's office has 55 auditors and inspectors in Iraq and about 300 reports and investigations already to its credit, far outstripping any other oversight agency in the country.