The investigation focused on three laboratory units: Explosives Unit, Chemistry-Toxicology Unit, and Materials Analysis Unit. Several broad areas of concern surfaced in the course of the investigation, particularly the impact of laboratory issues on criminal cases. The OIG did not find evidence of systemic contamination or improper evidence handling by laboratory employees but did raise serious criticisms of the performance of certain FBI employees. The FBI cooperated fully with the investigation and determined ineffective management within the laboratory resulted in problems being overlooked. In addition, the FBI agreed certain examiners failed to uphold high standards of professionalism. The FBI concurred with each of the 40 major recommendations contained in the OIG report and also adopted measures to improve the quality of the laboratory's work that exceeded OIG recommendations. Actions the FBI has taken in response to OIG recommendations are noted that relate to accreditation, laboratory restructuring, examiner reports, examiner training, and quality assurance. 1 photograph