An email sent 30 minutes after Tuesday's blast at Varanasi, in which the Indian Mujahideen (IM) claimed responsibility for carrying out the terror attack and warned of further attacks, is virtually impossible to trace and has frustrated investigators.
The e-mail was sent by getting into an unsecured wi-fi connection at a house in Navi Mumbai, officials of the state police's ATS said.
The e-mail was then bounced off several servers, with the final internet protocol address leading to a man named Binghui Gao, whose computer was on the China Unicom Heilongjiang Province Network in the Chinese city of Harbin.
Who sent the e-mail is a mystery, as has been the case with almost all IM communication.
The exception to this was the chance arrest of a car thief, Afzal Usmani, who blew the lid off the terror outfit that is an offshoot of the Pakistani-based Lashkar-e-Tayyaba. Usmani's arrest led the Crime Branch to software professional Mohammed Peerbhoy in September 2008.
Tuesday's e-mail was fed into the network on December 6 and programmed such that it would be sent only after the blast. This delayed e-mail configuration is commonly used by e-greeting websites, sources said.
"It will take a detailed investigation to trace the e-mail," a senior ATS officer said.
Mumbai police commissioner Sanjeev Dayal said the e-mail was similar to a series of e-mails sent in 2008 using unsecured wi-fi connections. For instance, an e-mail on August 24, 2008, was sent moments after Gujarat police claimed a breakthrough in the blasts that rocked Ahmedabad on July 26 that year.
In October 2008, the police claimed to have busted the cell behind these e-mails, arresting 20 suspected IM operatives.
"We launched an awareness drive (after 2008) and we plan to repeat it to make people realise the dangers of unsecured connections," Dayal said.
Focus on up link
As the email trail in Mumbai went cold, intelligence agencies are focusing on IM members reported to have been operating out of Uttar Pradesh and are hopeful of the Mayawati government's cooperation.
Security sources accused the UP government of being "less than enthusiastic" over previous plans by forces to crack down on IM operatives due to fears of a political backlash.
"We hope Tuesday's blast will nudge them to cooperate and act on the available information against suspected terror modules," a security officer said.