The Anti-Terrorist squad on Tuesday detained a man they believe will lead them to the mastermind—Lashkar-e-Taiba operative Zahibuddin Ansari—in the transporting and stocking of arms and explosives seized from Aurangabad and its neighbouring areas last week.Sources said the ATS picked up Bilal Ansari from Aurangabad and are grilling him on the whereabouts of Zahibuddin alias Zaby.ATS officials said they have found that Bilal was involved in the landing, transporting and storing of a consignment containing 43 kilograms of RDX, 16 AK-47 assault rifles, 50 hand-grenades, 3,000 AK bullets and 80 magazines, all of which were recovered from Aurangabad and Malegaon.‘‘He (Bilal) has played an important role in the chain. We will soon arrest him,’’ said ATS chief and Joint Commissioner of Police K P Raghuvanshi. ‘‘He definitely knows the kingpin well,’’ said another official.ATS officials said they suspect Bilal is also involved in activities of the banned Students’ Islamic Movement of India (SIMI) and has been in close contact with Zaby.