An FBI explosives expert working in one of the most important criminal investigations in US history - the Oklahoma City bombing - improperly tailored his conclusions to help build an incriminating case against the defendants.
The same expert took similar actions during the World Trade Center bombing case, according to a new report by the Justice Department's Inspector General.
The report is the result of an 18-month investigation of allegations of sloppy work and bias among officials assigned to the FBI's crime laboratory. The allegations were made by a lab scientist, Frederic Whitehurst, who first complained about questionable work in 1994.
Mr. Whitehurst has since been suspended from his job.
While the full impact of the report is unclear, it could help the defense in the Oklahoma City bombing trial - and may lead to the reopening of many other major criminal cases.
The report, released on April 15, will offer defense attorneys for Timothy McVeigh evidence of potential bias by federal agents. The lawyers could use such information to attempt to plant seeds of doubt in the minds of jurors.
Attorney General Janet Reno said the Justice Department has reviewed "thousands of cases" to determine whether new information about FBI lab work would undermine any convictions.
"So far, only 55 cases have been identified nationwide where prosecutors needed to be alerted," she says. Of those, Reno says, prosecutors notified defense attorneys of possible problems in 25 cases.
Questions about 13 of those cases have already been argued in court and all were resolved without any change in the outcome of the case, Reno says.
The Inspector General's investigation focused on the work of agents in three sections of the FBI crime lab, the explosives unit, the materials analysis unit, and the chemistry-toxicology unit.
Their work included some of the most significant cases in the country. In addition to Oklahoma City and the World Trade Center bombing cases, the investigation tracked lab work in cases including the O.J. Simpson case, the mail-bomb assassination in 1989 of US Circuit Judge Robert Vance, and the 1989 bombing of an Avianca Airlines flight near Bogota, Colombia.
The FBI lab has long enjoyed a reputation as the nation's premier crime lab, where the most up-to-date crime-fighting technology is paired with the nation's best investigators. Whitehurst's allegations, and now the inspector general's report, are taking some of the gloss off that reputation.
At the heart of Whitehurst's criticisms was the suggestion that FBI lab work was seen as an adjunct to the work of prosecutors, helping to make cases and convict suspected criminals. Whitehurst has argued that lab workers should be scientists, completely objective on the question of a suspect's possible guilt. He alleged that some FBI workers had stopped being scientists and had become tools of the prosecution.
In the Oklahoma City case, the inspector general found that agent David Williams authored a report in which he reached conclusions that could not be supported by scientific evidence.
His conclusions served the purpose of tying the defendants to the bomb scene. For example, he concluded that the explosive used in the bomb was ammonium nitrate and fuel oil. This conclusion was supposedly based on an analysis of the velocity of the explosion by studying the shrapnel damage of the blast. Based on that damage he found that ammonium nitrate and fuel oil was the explosive. But other explosives show the same characteristics, the report says.
Later, when questioned about his finding, Williams acknowledged that he reached that conclusion in part because Terry Nichols, one of the defendants, purchased ammonium nitrate and diesel oil prior to the bombing.
"We are troubled that the opinions in the Williams report may have been tailored to conform to the evidence associated with the defendants," the inspector general's report says. "These errors were all tilted in such a way as to incriminate the defendant."
The inspector general reached a similar conclusion about Williams's identification of the type of explosive used in the World Trade Center bombing and his testimony at that trial.
"Williams gave inaccurate and incomplete testimony ... that appeared tailored to the most incriminating result," the report concluded.