The integrated circuits (IC) used to assemble the bombs used in the eight Bangalore blasts, and 21 of which were planted but defused in Surat last week, were suspected to have been procured from sale outlets dealing in washing machine appliances.
The usually US-made ICs are used as delayed timers in washing machines, said senior blasts investigators and forensic experts.
The microchips used in these circuits, said an investigator who requested anonymity since he is not authorised to talk to media, were "very sophisticated and capable of multi-tasking, including delaying the detonation to up to a few days".
The officer, who has examined the ICs used to assemble the explosives detected by the Ahmedabad police, added that the chips did not have the initials of the manufacturer embossed on them that makes the task of tracking the manufacturing 'difficult'.
"These ICs are however sold at the rate of $3.95 a piece in the US and is commonly used in the washing machines used in India as delayed timers", the officer said. Investigating agencies suspect that the terror module/s involved in the bomb attacks could have procured the ICs from sales outlets dealing in washing machine appliances over period.
The investigating agencies are short-listing list of such potential outlets but considering their huge number it might not be easy to zero in the actual suppliers of the ICs used in the explosives.
Investigators suspect that the bomb-makers involved in the attacks in Bangalore, Ahmedabad and Surat could have been trained by a same set of trainers that are "masters in sophisticated bomb-making techniques and prone to improvisations". They suspect that the bombs planted in Surat which 'malfunctioned', could have been part of an experimental exercise to test the IC-based bomb technique for use in the future. Except the use of the ICs the Surat and Ahmedabad bombs are identical.
The attacks attest to the fact that the terror groups are using ingenuity in devising bomb-making and 'planting' techniques. "While they are spurning the use of RDX, they are not shy of using ICs, or planting the bombs inside concrete flower-pot shaped devices (since its compactness only increases the impact of the blast), or atop trees", said an officer.
Investigators are also probing a possibility that nearly two-dozen operatives, charged of smuggling in counterfeit Indian currencies, that were arrested in Navi Mumbai, Surat, Ahmedabad, Hyderabad, and Bangalore, in the last six months might furnish some information about the terror attacks. "The source of these currencies was Bangladesh… we have been monitoring a linkage between terror and counterfeiting activities that are used to fund the former," said a central intelligence officer.