The allegations against Christmas Day bomber, Umar Farouk Abdumutullab  -- that he carried a bomb laden with the explosive PETN sewn into his underwear aboard a flight bound for the U.S.  Passengers on board nabbed him when the explosive made a firecracker-like sound upon ignition -- are well known.

But TSA nominee John Pistole, currently Deputy Director of the FBI and deeply involved in the investigation of the failed bomb-attempt, revealed Thursday at his confirmation hearing how the terrorist got through airport security at his destination city without being detected.

"He was able to get through the screening in Amsterdam. He went through screening, but because of a concealment technique that was used where he had never touched it (the bomb)...explosive trace detection equipment even if done on his hands would not have picked up any explosive because he'd not touched it," Pistole recounted.

Under questioning from Sen. Byron Dorgan, D-ND, who said he supports Pistole as head of the airport security agency -- the third person nominated to that job under President Obama -- the nominee also said, "There were no metallic parts obviously, this was a chemical TA-TP PETN combination," referring to the explosive, saying no airport security equipment would have picked it up.

Pistole went on to say that the full body scan equipment, which has prompted privacy concerns from some, that has been deployed at some airports -- with many more to come -- would "hopefully" pick up the device, should another terrorist attempt the same kind of attack.  Pistole said TSA just needs to ensure proper training for screeners.