The stolen mobile phone of a prominent RSS leader was allegedly used to trigger the bomb blast near the BJP office in Malleswaram on April 17.

A top police source told Express: “We did a technical investigation of what triggered the improvised explosive device (IED) that injured 11 policemen and five civilians. Through a mobile tower near the bomb blast area we traced a number, which was registered in the name of a prominent RSS leader from Karnataka. We found out that the cellphone was stolen from him just a day before the blast.’’

The police source said they had traced more than one SIM card used for communication during the bomb blast operations, but the one stolen from the RSS leader was used to trigger the bomb. “The plotters used at least 16 stolen SIM cards for the blasts. We are still tracing the mobile calls and tracking them,’’ he said.

The Special Investigation Team formed to probe the blast has collected all relevant material, including CCTV footage of the person who parked the motorbike prior to the blast. A source said the footage showed that the suspect tried to park it in front of the BJP office gate twice, but security personnel stopped him. “The footage clearly shows him parking the mobike, with the front facing the road. His face is not clear in any of the shots as he is wearing a helmet,’’ the source said.

So far, nine suspects have been arrested in the case. But 16 other persons are suspected to be involved in the blast. “We are trying to trace them,’’ another source added.

Officials said they have more evidence in the present blast case than they had in the serial bomb blasts case in 2008 and the April 17, 2010, Chinnaswamy Stadium blast.

Suspects produced before court

Bangalore: Police on Tuesday produced blast suspects Rehamathulla (29), Asgar Ali (29), Hakeem (31) and Tenkasi Suleman (24), arrested from Salem jail, and Suleman (31), who was arrested in Coimbatore, before the ACCMM I court. The five were remanded in police custody till May 18, along with Kichan Buhari and Basheer, the other suspects.