Gurugram, Nov. 20 -- Police in Faridabad have obtained three years' worth of sales records from at least seven major fertiliser shops across Sohna, Nuh, Faridabad and Palwal as part of the investigation into the Red Fort blast, officers said on Wednesday. The objective, they said, is to determine whether accused doctors Umar-un-Nabi and Muzammil Shakeel Ganaie purchased fertiliser from these shops to assemble explosives. At least five shop owners were detained between November 12 and 15 at an undisclosed location in Faridabad but were released after nothing suspicious surfaced during questioning. Investigators, however, subsequently seized their sales data for a detailed audit to identify whether anyone had been periodically buying fertiliser in bulk. Officials privy to the probe said the records will be shared with the National Investigation Agency (NIA). In parallel, the Haryana department of agriculture and farmers' welfare is collecting stock and sales records from over 1,300 licensed fertiliser shops across the four districts. Police said the exercise stems from disclosures made during the interrogation of Dr Ganaie, his associate Dr Shaheen Shahid, and other suspects arrested during the crackdown on the alleged "white-collar" terror module. Between November 8 and 9, investigators recovered 2,900kg of ammonium nitrate and other explosive materials, leading to a probe of local supply chains. Several traders recounted being picked up for questioning with little warning. A 65-year-old owner of an outlet in Sohna, said he had already turned over all documents. "I was detained in a room for three days with six other traders," he said. "We are licensed shop owners who follow government norms. Hundreds of farmers visit us daily. It is impossible for us to know who is buying fertiliser for legitimate farming," said the shop owner's brother. Another shop owner said his 21-year-old son was taken away on November 12 while he was in Agra for a family wedding. "He was released on November 15. We have cooperated fully, but now there is suspicion in the market. My son was caring for my ailing mother, who was left alone," he said....