Official sources said the manner in which a wrist watch was used as a timer to complete the bomb circuit to trigger the detonators kept on three newly-bought bicycles, two dustbins and a polythene bag was similar to the technique adopted by IM, which has links with terror groups in Pakistan.
Joint Commissioner of Pune City Police Sanjiv Singhal said 33-year-old Dayanand Patil, the lone person injured in the blast near Bal Gandharva theatre, was being 'interrogated'. He also said there has been no arrest or detention so far.
Patil's wife Satyakala and some bicycle shop owners in the city's Kasaba peth area were also questioned as part of the investigation. Police said Patil was not being treated as a suspect as of now but was being questioned by police as to how the explosives found its way into his carry bag.
As investigators pieced together evidence, the sources said ammonium nitrate was apparently used to make the explosives with Neogel as a binding agent.
Four serial explosions in the space of less than one hour rocked a single area in the crowded Jangli Maharaj(J M) road last night. One explosive was partially detonated while another was defused, the sources said.
The investigators are not ruling out terror angle and trying to zero in on the outfit behind the blasts on a day when the new Home Minister Sushilkumar Shinde took charge. Shinde cancelled a scheduled visit to Pune in the evening before the explosions struck Pune.
Shinde said the Centre has taken the explosions "very seriously" and investigators were looking for clues.
"We have taken it very seriously," he told reporters in New Delhi after a high-level meeting which reviewed the security situation in the country in the wake of the blasts. (MORE)