A CID official said that after verification of the SIM card confiscated from the arrested two women Rajira Bibi alias Rumi and Amina Bibi it was found that they used to make frequent calls to other states including J&K and Mumbai.
The investigators have also seized a computer from a cyber cafe in Burdwan, which was frequented by suspected terrorist Kausar. The slueths have taken the hard disk of the computer and are trying to decode it.
The sleuths are yet to know where those explosives were delivered by Kausar.
The two dead terrorists were experts in chemical bomb making and the materials and money needed for making the bombs were supplied by Kausar.
Four persons, including two women, have so far been arrested in connection with the grenade explosion at Khagragarh in Burdwan district which left two suspected terrorists dead.
The other two persons arrested are Hakim, who is undergoing treatment at the Burdwan Medical College and Hospital, and Hafez Mollah alias Hasan.
Meanwhile, Sukul Seikh, a shop-owner, was today detained for interrogation at Kirnahar village in Birbhum district, where President Pranab Mukherjee's elder sister lives, in connection with the explosion.
Police sources said that Kajal Seikh, son of Sukul Seikh, was friend of Seikh Kadar who was the brother-in-law of Kausar.
