Searches were conducted at various places including the rented residence of deceased Shakil in Beldanga, Murshidabad in West Bengal by the team of the National Investigation Agency and West Bengal CID.
Certain documents and metal pieces used in making IEDs have been recovered. A thorough search has also been initiated at the Simulia madrassa in Burdwan where the accused were allegedly radicalised in jihadi ideology.
Joint teams of West Bengal CID, the NIA and central intelligence agencies are interrogating the three persons who were arrested following the blast -- two women, Razia and Amina, and Badrul Alam Molla.
The case pertains to an explosion at a rented house at Khagragarh on October 2 in which two persons, believed to be members of Jamaat-ul-Mujahideen Bangladesh, died. The matter is being investigated by the NIA's Kolkata branch after it registered a case on Friday to probe the matter.
Section 6(5) of the NIA Act, 2008, empowers the Centre to suo motu direct the agency to investigate a scheduled offence committed anywhere in India.
The decision to hand over the case to NIA was taken by the Centre in view of the international ramifications of the case following suspicions that some Bangladeshis might be involved in the incident.