The use of ammonium nitrate-based explosive and shrapnel, like nails, ball bearings or steel balls, to cause maximum casualties in the improvised explosive devices (IEDs) planted in Mumbai is an indication of involvement of the Indian Mujahideen (IM) or its remnants in some new avatar.
According to preliminary reports, mobile phones were used as timer device in the IEDs planted in Mumbai. Experts have found traces of the TNT with ammonium nitrate in the IEDs. Interestingly, Hindu extremists used cellphones as timer device in the IEDs exploded at Mecca Masjid and Ajmer Shraif. But sources said this might be an effort to give conflicting signals to investigators.
According to a comparative study, the IM jehadis have used ammonium nitrate with different other chemicals in at least six terror strikes between August 2007 and September 2008.
The IM had used NEOGEL 90, an ammonium nitrate-based explosive used for commercial purposes, in Hyderabad (Gakul Chat and Lumbini Park blasts on August 25, 2007) and the UP court blasts (in district courts in Lucknow, Varanasi and Faizabad on November 23, 2007).
In Jaipur (May 13, 2008), Ahmedabad (July 26, 2007) serial blasts and a failed operation in Surat(July 27, 2008) ammonium nitrate emulsion was used.
For Delhi serial blasts on September 13, 2008, only ammonium nitrate was used.
In Hyderabad, UP courts blasts and Jaipur serial blasts, the IM used ball bearings as shrapnel. The IEDs used in Ahmedabad and Surat had nails and steel balls while in Delhi serial blasts only steel balls were used. In all cases, a nine volt battery was used to charge the IEDs.
Except for Surat, in all other blasts, a mechanical quartz alarm clock of same make was used with two detonators linked to the battery.
Most of the electric detonators were of the Andhra Pradesh Explosive Ltd make while in some cases detonators made by the Rajasthan Explosives and Chemicals Ltd were also used.
Forensic experts will match these details with the IEDs exploded in Mumbai. Since no unexploded IED has been recovered, their task is all the more difficult.
It seems a lot of thought has gone into the making of IEDs for Mumbai. One IED was cleverly fitted in an umbrella, knowing that it would be very difficult to spot during monsoon.