Calcutta, Oct. 15: The everyday but graceless act of scribbling a phone number on a palm and then a vigorous attempt to rub it off have provided a vital lead to investigators probing the Burdwan blast.

While interrogating Abdul Hakim, who survived the October 2 explosion with injuries and is now in SSKM hospital in Calcutta, a Bengal police officer noticed that the suspect was trying to rub his left palm with his right thumb as if his skin was itching.

Scribbled on the palm was a mobile number (96096*****). The number was found to be that of Reza-ul-Karim, a suspect who is absconding.

“The number matched the last one dialled from Hakim’s wife Alima Bibi’s cellphone minutes after the blast. That more or less established that the Hakim family and Karim had links,” said an investigator who requested anonymity. Alima Bibi is now in custody.

The account of the investigators could not be independently verified.

The investigators said call records of the number helped them identify more possible operatives. Officers of the National Investigation Agency (NIA), which has taken over the probe amid allegations of evidence tampering by Burdwan police, applauded the local police for spotting the palm-scrawled number and pursuing the lead.

“It is a big thing to unearth so many leads from one contact. Analysing these numbers could be of great help to the investigation,” said an NIA officer.

The police raided Karim’s home in Burdwan’s Badshahi Road — not too far from the blast-hit Khagragarh flat and the Baburbag address of Kausar Ali, another key operative of the terror module — but he had fled by then.

“Using the data sourced through the number, we are getting more details about the extent to which the terror network had spread and the operatives of the module,” a source said. “Karim is absconding but we are getting more information by analysing his call records.”

Hakim, who started “co-operating” after allegedly insisting for 48 hours that “I have no faith in the Indian police”, has told the investigators how the number was scribbled on his palm.

“Karim’s number was saved in the mobile phone of Shakil Ahmed (one of the two persons who died in the Burdwan blast). But Hakim told us that they were trained to destroy all traces of evidence if anything went wrong…. That day, soon after the blast, Alima and Gulshan set out to destroy evidence, starting with Shakil’s phone. At the same time, they needed help to get out of the place,” an investigator recounted, based on information provided by Hakim.

Hakim apparently told the investigators that before destroying Shakil’s phone, Alima had read out Karim’s number and told Hakim to call him for help.

“I couldn’t see any piece of paper and I jotted down the number on my palm in a hurry. Then I called Karim on Alima’s phone, informing him of the blast and seeking urgent help,” the investigator quoted Hakim as saying.

Karim, instead of coming to help, probably sniffed danger and fled from his house.

When the police reached the Burdwan flat where the bomb exploded, they found Shakil’s half-burnt phone and two intact phones of Alima and Gulshan Bibi, the wife of Shakil who died in the blast.

The investigators could not find the phones of either Hakim or Subhan Mondal, the second casualty of the explosion. It is suspected that the phones were either damaged in the blast or deliberately destroyed.

Investigators trailing the number on Hakim’s palm initially stumbled upon an address at Bhutbagan of Raghunathpur in Murshidabad but found no trace of Karim.

The call records showed that “30 calls were exchanged between Karim’s number and another number in Raghunathgunge (a locality in Murshidabad but different from Raghunathpur). The holder of the number turned out to be Karim’s wife. The tower location suggested that Karim was calling her from Burdwan’s Badshahi Road”, the investigator said.

It is on the basis of this information that a raid was carried out at Badshahi and it was established that Karim had stayed at a house there before fleeing. The investigator clarified that Karim’s wife is not a suspect in the case.

Investigators said Karim’s number was also used to make at least 32 calls to a number belonging to one Rahman Sahadur of Taranagar in Lalbagh and several calls to one Nasir.

“We are looking for these people as they may help us unearth more details,” said an officer.

Hakim, who had been quizzed by both the state and central agencies on the hospital bed, reportedly said he had met Shakil at the Shimulia madarsa where he went for a job after passing Madhyamik from his hometown at Mohammad Bazar area in Birbhum. At the madarsa, he met Alima.

“Shakil would frequent the madarsa for reasons that Hakim claimed he did not know at that time…. Later, he was offered a job at Shakil’s tailoring shop at Baduapara in Beldanga, where he shifted with Alima,” said an investigator.

It was there that Hakim’s indoctrination had begun.

“Hakim claimed that he was given training to make explosives,” the officer added.