Two calls received by a particular cell phone in Varanasi's Dashawamedh Ghat area are believed to have provided major leads to the National Investigation Agency (NIA) probing the December 7 blast in the holy city. Two people were left killed and 30 injured in the blast.
NIA and Intelligence Bureau (IB) are now trying to zero in on the owner of the cell phone to which these calls were made from Bhendi Bazar area in Mumbai, officials said.
While one call was received December 6, the second call was received shortly before the blast at the Shitla Ghat when devotees were performing the evening arti on the bank of the Ganga river.
A special NIA team is camping in Varanasi, and another team has flown to Mumbai to track down the caller, who could again provide very vital clues to the terrorist strike, officials said.
The calls were traced by scanning all the calls made and received on the day through the telecom tower installed in that neighbourhood.
"What intrigued us was that only two calls were received on that cell phone, which went off soon after the blast," disclosed an IB sleuth.
"The fact that neither was the cell phone used for making any call nor did it receive any other call at all further arouses suspicion that it was purchased with a limited purpose," he said.
What has further confirmed the suspicion was the fake address proof and identity used for issue of a SIM card.
"The SIM card was purchased from a shop in Mau district, 60 km from Varanasi and a ration card bearing the name of Vijay Kumar was used as proof of address and identity. However, the card and the address were both found to be fake," the official said.
The shop-owner who sold the SIM card was picked up by the anti-terrorist squad (ATS), "essentially to assist the investigation agencies in tracking down the person who purchased the SIM card". However, the ATS had drawn a blank so far.
While there was reason to believe that the low-intensity blast was masterminded by some Indian Mujahideen agents camping in Sharjah, some threads were earlier also traced to Azamgarh. However, investigators believe that the SIM card could be a key to the blast's perpetrators.