Two Improvised Explosive Devices (IEDs), packed in metal pipes and fitted with timer devices, were used in the twin blasts in coaches S 4 and S 5 of the Bangalore -Guwahati tri-weekly Express when it reached Platform No 9 at Chennai Central on Thursday morning.
Forensic and Bomb Detection and Disposal Squad (BBDS) experts involved in the examination of the scene of crime ruled out the usage of RDX and TNT. Examination of the coaches indicated that the explosions had just damaged the seat and the glass panes in the window, clearly indicating mild intensity explosions.
Also, the fact that the side walls of both the coaches were intact and the absence of any serious injuries to passengers led the investigators to believe that the motive was just to trigger panic rather than a major explosion that would have claimed more lives or left many injured.
The victim, Parachuri Swati (24), lost her life having borne the brunt of impact of the explosion as the object was placed right under her seat.
The fact that no black smoke was visible near the scene of occurrence confirms the theory of the bomb disposal experts. Ammonium Nitrate is believed to have been used to make the explosive, with steel balls and nails used as shrapnel. These were packed tight using cloth and kept in two back bags.
The material used for the explosive could have been sourced from a chemical storehouse or even a quarry as white and bluish smoke was seen emanating from both coaches.
“The impact, the make and appearance of the suspected object that triggered the explosion seem to be strikingly similar for both bombs,” said experts adding that the recovered objects indicated that the bomb was a well-assembled device. Parts recovered from the scene of crime, along with two similar clocks used for setting the time, have been sent for forensic examination.
