The U.S. Justice Department calls it the biggest case of laboratory fraud in the nation’s history, and the scandal affects 59,000 toxic clean-up sites in the U.S. After a two-year probe of the Intertech Laboratory in Richardson, Texas, 13 former employees had been criminally charged in connection with widespread falsification of environmental test reports. The defendants deny the charges. The reports called into question influenced clean-up decisions at a range of government and private toxic spills, including leaky underground fuel tanks and Superfund sites. Paul Coggins is the U.S. attorney for the northern district of Texas. He explains the indictments.