Delhi police's anti-terror officials have for now ruled out involvement of right-wing Hindu outfits, which are under the scanner for having allegedly executed blasts in Malegaon and Gujarat's Modasa, in the low-intensity blast in Mehrauli on September 27.
The reason, said a senior police official who requested anonymity since he is not authorised to speak, is that the "signature (type) of the explosive used in Mehrauli was different from those used in Modasa and Malegaon".
The officer added, "Low-intensity explosives were used in three places but they were not identical. The timer mechanism used in Mehrauli was different from the one used in Malegaon/Modasa that indicates the former was the handiwork of a separate outfit."
"In Mehrauli, the bomb was timed by its acidic contents, while in Malegaon/Modasa the bomb was set off by a timer based on the batteries of the bikes used to plant them," the officer said.
Maharashtra's Anti Terrorism Squad has arrested three former members of Indore-based Hindu Jagran Manch for their alleged involvement in the Malegaon blasts.
The Mehrauli blast that occurred in a congested, commercial area had led to the death of a nine-year-old kid.
The south Delhi police which is probing the blast has so far made no headway in the case - there are neither arrests nor any identification of the suspects/group involved in the attack. The police had initially suspected that a group that was involved in a blast at Jalpaiguri in West Bengal could be linked to the Mehrauli blast as well.
Delhi police's special cell, which cracked the case involving the September 13 serial-blasts across five spots in the city, is not part of the probe.