"But this is the result of preliminary investigation. Rigorous investigations are in progress," Bansal said pointing that the traces of the explosive found were not conclusive.
PETN is a very powerful and destructive explosive as it is difficult to detect because of its plastic nature and can easily pass metal detectors. Even bomb-sniffing dogs can not detect it because of its low pressure molecules. It allows terrorists to use it in small quantity which can propel huge damages. Sources said that even 100 grams of PETN is enough to blast away a car.
Same explosive was used in 2001 to explode an American Airlines Jet to Miami by terrorist Richard Reid, commonly known as the 'shoe bomber'. Al Qaeda operative Umar Farouk Abdulmutallab was also found with the same explosive in his underwear when he attempted to explode a bomb in Northwest Airlines Flight 253, which is also known as Christian Day bomb plot, in 2009. The same explosive was also found in two cargo planes from Yemen to the US in October 2010.
Bansal said, PETN is "an explosive of choice for terrorists" as it was easy to carry. The oddments of the Delhi high court bomb were being analysed in a forensic laboratory, he added.