The investigation into the July 13 Mumbai serial blasts case, which has yielded no results so far, may have hit a big hurdle.
Forensic reports prepared by the National Security Guard (NSG) and the National Investigation Agency (NIA) differ on the type of explosives and timer devices used to set off the blasts at Opera House, Zaveri Bazar and Kabutar Khana in Dadar that killed 26 people.
According to NIA sources, their experts found that the three bombs were made up of a mixture of ammonium nitrate and fuel oil (AnFO) and did not have a high-intensity explosive such as RDX or PETN as a booster.
However, the NSG's post-blast study team, part of its National Bomb Data Centre, has come to the conclusion that trinitrotoluene or TNT was used as a booster, sources said. TNT is mainly used for blasting during civil works.
The two agencies also disagree on the nature of the device used to set off the bombs. While NIA's experts failed to find any remnants of a timer device and are, therefore, silent on it in their report, the NSG experts claim to have found remnants of an electronic chip.
"The NSG report says an electronic timer, suspected to be that of a cell phone, was used to trigger blasts," said an investigator on condition of anonymity.
Maharashtra's forensic science laboratory has only been able to establish the use of AnFo.
"Our forensic experts have not yet been able to find anything more than that. They are still analysing some of the articles recovered from the blast sites," the investigator said.
The discrepancies have made the work of the Anti-Terrorism Squad of the Mumbai Police, which is probing the case, more difficult.
"Accurate forensic analysis is important to establish the type of bomb used," an investigator said.
"It is the first step to zero in on the group involved because every group's bomb-makers have their own methods and combination of explosives and devices."