The Justice Department inspector general's office has determined that the FBI crime laboratory working on the Oklahoma City bombing case made scientifically unsound" conclusions that were "biased in favor of the prosecution," The Los Angeles Times reported. The still-secret draft report ... also concludes that supervisors approved lab reports that they "cannot support" and that FBI lab officials may have erred about the size of the blast, the amount of explosives involved and the type of explosives used in the bombing. The draft report shows that FBI examiners could not identify the triggering device for the truck bomb or how it was detonated. It also indicates that a poorly maintained lab environment could have led to contamination of critical pieces of evidence. The investigation into the crime lab practices began in 1996 following complaints from FBI chemist and whistle-blower Frederic Whitehurst. The draft report's harshest criticism was of David Williams, a supervisory agent in the explosives unit. "We are deeply troubled by Williams' report, which contains several serious flaws," the report said. "These errors are all tilted in favor of the prosecution's theory of the case. We conclude that Williams failed to present an objective, unbiased, competent report." Those flaws reportedly include the basis of his determination that the main charge of the explosion was ammonium nitrate. The inspector general called such a determination "inappropriate," the Times said.