Investigators looking into the July 13 bombings in Mumbai have extended their probe to various parts of the country as they intensify the hunt for clues leading to those behind the terror attack, informed sources said on Monday.
Five days after the triple blasts, which killed 19 and injured 129, sources close to the investigation said forensic sleuths were also trying to decipher the exact make of the detonators used to trigger the bombs made of ammonium nitrate, fuel oil (ANFO) and ball bearings.
What is known is that the blasts were triggered by using timers and not remote controlled devices.
"But what timer device it was is still not known. It could be clock timers, it could be mobile phones alarms, it could be any other timer device, mechanical, chemical or digital," said a home ministry source in New Delhi.
Sources familiar with the probe process said the identification of the timer device was crucial because it would help investigators establish a pattern and trace similarities, if any, to previous attacks.
This would give the investigation a definite angle and maybe point to the outfit behind the blasts.
The homegrown Islamist militant outfit, the Indian Mujahideen, has used timer devices of various kinds to trigger blasts in many Indian cities, an expert said.
Though authorities have refrained from naming any terror outfit, sources told IANS that the Maharashtra Anti-Terrorism Squad (ATS) and the National Investigation Agency (NIA) had raided various places for suspected Indian Mujahideen operatives.
They have also questioned some arrested activists of the outfit in jails in Uttar Pradesh, Gujarat, West Bengal, Andhra Pradesh, Karnataka and Madhya Pradesh.
An NIA team questioned Jalees Ansari, convicted for his alleged role in the 1993 Mumbai serial blasts, in an Ajmer jail.
Ansari, an expert in handling explosives, is serving a life term. The sources said he could have possibly helped the perpetrators to make the bombs.
An NIA team is also likely to visit Bihar where police have taken into custody two suspected operatives of the Harkat ul Jehad-e-Islami (HuJI) Riyaz ul Sarkar and Aftab Alam.