Ansari, hailing from Darbhanga district of Bihar, was remanded in police custody till May 29, Maria said, adding that a supplementary chargesheet, mentioning Ansari's name as well as further probe details, would be filed soon.
Twenty-seven people were killed and 130 injured when three explosions ripped through the crowded areas of Opera House, Zaveri Bazaar, and Dadar (west) in Mumbai on July 13 last year.
The ATS had earlier arrested four accused, Naquee Ahmed, Nadeem Shaikh, Kanwar Pathrija and Haroon Naik in the blasts case. The chargesheet against them was today filed in a special court of the Maharashtra Control of Organised Crime Act on Mumbai.
Ansari, a "close aide" of Yasin Bhatkal, had been nabbed in February by a team of the Delhi police's special team from Darbhanga.
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