The investigating team visited the factory yesterday where Abdul Hakim alias Hasan Sahib had been recruited about a fortnight before the blast on October 2, and collected samples of raw materials from the factory at Saraitikar village, in Santipara area, 1 km from the Khagragarh flat, where the blast occurred, NIA sources said.
Chemicals rich in aluminium and lead had been seized from the Khagragarh flat besides explosives after the blast and they would be matched with the samples collected from the wok (kadhai) factory, the sources said.
The team members interrogated Sheikh Zakir Mir alias Sheikh Laltu, the owner of the wok factory where Hakim had been employed for a daily wage of Rs 100. Hakim is now undergoing treatment for his injuries sustained in the blast at SSKM hospital in Kolkata.
Mir revealed that Hakim who was then residing at Khagragarh, had told him that he was a resident of Mangalkot, near Simulia, 60 km from Bardhaman town.
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The sources said Hakim could carry on his terror activities at the Khagragarh flat, a stone's throw away under the garb of a factory employee with access to the alloys used in woks for the purpose of making explosives.
The factory, employing ten workers which was closed for the Durga pujas before the October 2 blast, has remained shut since as the workers have left, the factory owner said.
NIA officials detained a suspect in connection with the blast and took him to Kolkata for interrogation yesterday, the sources added.