DENVER: Timothy McVeigh's attorneys suffered a major defeat Tuesday when the judge in the Oklahoma City bombing trial barred further questions about the scathing federal report on problems in the FBI crime lab. The defense had hoped to use the report to cast extensive doubt on the physical evidence that the FBI lab examined, and disqualify the prosecution's FBI expert testimony. But the judge, during cross-examination of FBI chemist Steven Burmeister, barred discussion of the larger problems in the FBI crime lab, including those documented in a highly critical Justice Department. The report, released in April, found that FBI scientists had produced flawed work or slanted their findings in favor of the prosecution in this case and other high-profile criminal cases. The defense was barred from questioning Burmeister about new laboratory procedures put in place since the bombing, about recent steps taken to have the lab accredited by an outside agency and a former FBI chemistry-toxicology unit chief who handled some of the bombing evidence and who has been severely criticized. In earlier testimony, however, Burmeister acknowledged one point that may stick with the jury: he found no traces of explosives in McVeigh's car or in storage facilities in Kansas, Iowa or Arizona where McVeigh allegedly kept the main ingredients for the weapon.