"Sewage pipes in the skyscraper broke during the explosion. depositing 80 gallons of sewage throughout the wreckage.
The Treasury Department's Bureau of Alcohol, Tobacco and Firearms (ATF) asked Dr. Whitehurst to analyze some of this sewage, thinking it was an explosive substance. "Transcript. pg. 16333".
Dr. Whitehurst concluded that there was no sound scientific basis for the government's public claim that a urea nitrate bomb had been the source of the explosion. When he refused to recant or to doctor his reports to support the urea nitrate bomb theory, the FBI used an unqualified lab technician to testify that the so-called urea nitrate found at the scene was consistent with a urea nitrate bomb.
Dr. Whitehurst submitted two blind test samples to the lab technician. Whitehurst had prepared one sample by urinating into a laboratory flask. The other was a sample of commercial grade fertilizer prepared by FBI Agent Burmeister. The lab technician found that both samples tested positive for urea nitrate, the explosive component of the infamous fertilizer bomb. In other words, Dr. Whitehurst proved that the lab technician, like the ATF, couldn't tell a bomb from sewage. The following pages are taken from the transcript of the New York trial for the bombing of the World Trade Center in 1993.
This is one reason I distrust whatever the FBI crime lab is pressured to produce.