A month has gone by after the blast that rocked south Delhi's Mehrauli area and led to the deaths of three persons, but the police investigation is yet to make any headway in the matter.

Investigators have so far failed to find any clue about the two motorcycle-borne men, who masked themselves in helmets and dropped the ‘loosely-packed crude bomb’ hidden in a polythene bag in Mehrauli market on September 27, a fortnight after the serial blasts rocked the capital.

The hunt for the two motorcyclists is still on and police have formed several teams for catching them, a senior official said.

With the arrest of three persons, including a 'Sadhvi', in Maharashtra for their alleged involvement in the September 29 Malegaon blast, the police are also probing whether any Hindu outfit is behind the incident.

"We are probing all angles. But so far nothing has emerged as to the involvement of any religious group in the Mehrauli blast," a senior police official said.

With no one claiming responsibility for the explosion, initial suspicion fell on Bangladeshi nationals and local criminal gangs as there were at least three mysterious blasts in south Delhi this year.

Police had earlier virtually ruled out the involvement of Indian Mujahideen, which is believed to be behind the serial blasts, saying the bomb which exploded in the market had no ‘signatures’ of any terrorist outfit.