Towards the end of 2007, sources said, it was clear — based on forensic and scientific evidence available until then — that India was being hit by two kinds of bombs that were distinguished not so much by the chemical used as explosive but more by the “character” of the bomb itself, its circuits and elements.

The first were the C-shaped open wooden boxes that held the circuit through holes on the side for wires to pass. The explosive was essentially tightly packed ammonium nitrate, held together by fuel oil or nitrogen gel, metal balls and nuts for splinters and had an alarm clock for a timer (the famous Prince or Samay watches). These were the ones which went off in UP, Ahmedabad, Bangalore, Delhi, and, possibly, even Jaipur.

The second type of bombs were mostly found in metal pipes with grooves in single rows on one side and spiraled on the other. These pipes were filled with explosives, not always the same type and this is what initially confued the investigators. But they were usually in tin boxes or a suitcase. Strikingly similar here were bombs found in the Samjhauta Express last February, Mecca Masjid blasts last May, and Ajmer Sharif blasts last October. So investigators concluded that there were two groups with two distinct styles of bomb-making at work.

With the arrest of Indian Mujahideen cadre in Maharashtra, the Batla House encounter and the recent arrest of Qayamuddin Kapadia, security agencies believe they had cracked the first group — essentially IM cadres who got their almost C-shaped boxes with ammonium nitrate from somewhere in Karnataka. So the search intensified for the second group.

There was no frenzy until the arrests of Sadhvi Pragya Singh and Lt. Col Purohit stayed confined to investigations into the September 29 Malegaon blasts. Largely because no unexploded device was found in Malegaon and forensics revealed little about the type of bomb except confirming the explosive to be ammonium nitrate with the state authorities claiming traces of RDX. No meaningful forensic comparison could be made with other blasts, said sources.

However, revelations claimed by ATS after interrogation of the accused about Ajmer and Samjhauta have suddenly pushed investigators across at least five states into action with security agencies here asking the question: Could this be the elusive second group?

The one unknown fact being that the suitcase bomb in Samjhauta, and the tin boxes that held the bombs in Mecca Masjid and Ajmer Sharif had one common factor — an identical arming device. This was a small suitcase lock fitted into these boxes that had to be turned by a key for the device to be armed. After that the detonation could be through a digital timer or a remote controlled device like a mobile phone. Identical locks were found in all the unexploded bombs recovered at these three sites. So once ATS claimed that Purohit had said something about these blasts, the interest multiplied several times. More so, the last investigative trail led to Indore from where Pragya Singh worked as an ABVP activist.

The other temptation for investigators here is that potassium chlorate was used in Samjhauta (Central agencies say there was no RDX while Haryana forensics is said to have claimed presence of RDX traces), placed in a suitcase with a similar arming device as found in Mecca Masjid and Ajmer but filled with fuel bottles to give an incendiary effect. The explosion was not big, but as is known the fire caused by the fuel bottles is what killed people. Most of the wounded had burn injuries.

Potassium chlorate is used commonly in fire crackers and here is where the accidental explosion in Nanded in 2006 assumes relevance. Scores of fire crackers were found from the spot and several of them were empty cases where the powder from inside had been removed and stored separately. A few days later, pipes with explosive went off in Jama Masjid. It was of low intensity and crude, but one of the first bombs in the second category to be used.

More interestingly, on Nanded, the interrogation account available with agencies reveals that the two men, who were killed, had removed the circuit of a remote controlled toy and were trying to see if it works by way of a remote control. In fact, one of the survivors feared that he was switching channels on a television remote and that, perhaps, triggered the explosive. The Nanded bombs were, in fact, meant for a mosque in Aurangabad, said sources.

This was 2006 and a year later, a cellular phone was used as a remote trigger in Mecca Masjid even though the explosive used for a mix of RDX and TNT.

The unanswered question in all of this is whether the people allegedly behind Malegaon are also linked with any of these three. Here, sources said, there is almost no link from the forensics side and so, narco-confessions would need to be strengthened with more empirical evidence. As of now, the Mumbai ATS is confident but police teams from Haryana, Andhra Pradesh, Gujarat and Rajasthan are yet to join the dots.

Ally Nitish says not with BJP on Sadhvi, apply law sternly

Ally Nitish Kumar, who heads a JD(U)-BJP govt in Bihar, says “we are not with BJP on Pragya Thakur, we condemn terrorism in any form, want rule of law be applied sternly”

* Nashik court extends till Nov 29 judicial remand of Sadhvi, seven others in Malegaon blast case

* Court rejects Gujarat police plea for interrogation of nine accused

* Sadhvi lawyer alleges ATS subjecting client to mental, physical torture

* BJP, Sena activists crowd court premises, raise slogans in favour of blast accused.