Islamabad, Oct 24: The suicide bomber who attacked former premier Benazir Bhutto"s reception rally in Karachi used a manual trigger to detonate the explosives, sources in the Interior Ministry have said.
The investigation report submitted to the Interior Ministry stated that no crater was found at the epicentre of the suicide attack, they said.
It also said that no hand grenade pieces or splinters of any type of shell or mortar bomb were recovered from the crime scene.
According to the sources, the report revealed that the blast shattered windows located 170 feet away from the epicentre.
It said investigators had recovered the body of a damaged striker sleeve (MUV-2) from the crime scene.
The report said that the scalp of one suicide bomber was found 78 feet from the epicentre.
Investigators also recovered ball bearings that had riddled bodies and vehicles from the crime scene. The bearings travelled in all directions and 63 struck the VIP truck carrying Bhutto, but could not penetrate the armour plating.
The report states that approximately 10 to 12 kilograms of explosive material was used in the second bomb, which was carried out by a suicide attacker, while the first bomb contained less explosive material.
The exact quantity of the explosives used by the first bomber or whether he was a suicide bomber could not be discovered, the Daily Times reported.
The report also revealed that the suicide bomber exploded himself near the police mobile following the first blast.
Investigators believe that another suicide bomber, who was probably wearing a jacket with low quantity explosives to confuse the security men around the truck carrying Bhutto, might have caused the first blast.
The report mentioned that one private vehicle was completely burnt. It said that the blast waves also hit the VIP truck, but their effect was minimised because it was bullet proof.
Also, the truck"s height, 16.2 feet, allowed the open atmospheric pressure to decrease the intensity of the explosion to a minimum.