were detected on three samples of material from three separate locations of the recovered airplane wreckage (described by the FBI as a piece of canvas-like material and two pieces of a floor panel). These samples were submitted to the FBI's laboratory in Washington, DC, which determined that one sample contained traces of cyclotrimethylenetrinitramine (RDX), another nitroglycerin, and the third a combination of RDX and pentaerythritol tetranitrate (PETN); these findings received much media attention at the time. In addition, the backs of several damaged passenger seats were observed to have an unknown red/brown-shaded substance on them. According to the seat manufacturer, the locations and appearance of this substance were consistent with adhesive used in the construction of the seats, and additional laboratory testing by NASA identified the substance as being consistent with adhesives. Further examination of the airplane structure, seats, and other interior components found no damage typically associated with a high-energy explosion of a bomb or missile warhead ("severe pitting, cratering, petalling, or hot-gas washing"). This included the pieces on which trace amounts of explosives were found. Of the 5% of the fuselage that was not recovered, none of the missing areas was large enough to have covered all the damage that would have been caused by the detonation of a bomb or missile. None of the victims' remains showed any evidence of injuries that could have been caused by high-energy explosives. The NTSB considered the possibility that the explosive residue was due to contamination from the aircraft's use in 1991 transporting troops during the Gulf War or its use in a dog-training explosive detection exercise about one month before the accident. Testing conducted by the FAA's Technical Center indicated that residues of the type of explosives found on the wreckage would dissipate completely after two days of immersion in sea water (almost all recovered wreckage was immersed longer than two days). The NTSB concluded that it was "quite possible" that the explosive residue detected was transferred from military ships or ground vehicles, or the clothing and boots of military personnel, onto the wreckage during or after the recovery operation and was not present when the aircraft crashed into the water. Although it was unable to determine the exact source of the trace amounts of explosive residue found on the wreckage, the lack of any other corroborating evidence associated with a high-energy explosion led the NTSB to conclude, "the in-flight