On Friday, 19 February 2010, the U.S. Department of Justice announced the conclusion of its investigation into the 2001 anthrax attacks. The DOJ maintains that Dr. Bruce Edwards Ivans, who in 2002 passed a polygraph test regarding the anthrax attacks, was the sole perpetrator.
In an investigative summary (640 kb PDF), the DOJ characterizes Ivins’ passing of the polygraph as part of an effort to “stay ahead of the investigation,” alleging (at p. 84, fn. 51) that he used countermeasures to fool the polygraph:
In some sense, Dr. Ivins’s efforts to stay ahead of the investigation began much earlier. When he took a polygraph in connection with the investigation in 2002, the examiner determined that he passed. However, as the investigation began to hone in on Dr. Ivins and investigators learned that he had been prescribed a number of psychotropic medications at the time of the 2002 polygraph, investigators resubmitted his results to examiners at FBI Headquarters and the Department of Defense Polygraph Institute for a reassessment of the results in light of that new information. Both examiners who independently reassessed the results determined that Dr. Ivins exhibited “classic” signs of the use of countermeasures to pass a polygraph. At the time the polygraph was initially examined in 2002, not all examiners were trained to spot countermeasures, making the first analysis both understandable under the circumstances, and irrelevant to the subsequent conclusion that he used countermeasures.
Although the summary doesn’t state what “classic” signs of countermeasures Ivins allegedly displayed, Michael Isikoff of Newsweek reported in 2008 that the FBI “concluded he’d used ‘countermeasures’ such as controlled breathing to fool the examiners.”