New Delhi, April 12 -- Investigators on Friday began grilling 2008 terror attack key accused Tahawwur Rana about his co-conspirators in Pakistan and were set to confront him with a "protected witness" who allegedly received David Coleman Headley in Mumbai in 2006 as well as arranged logistics and accommodation for him, according to senior officials and investigation details seen by HT .

The interrogation by officers from the National Investigation Agency (NIA) and other intelligence agencies began hours after a special court in Delhi sent Rana to 18 days in NIA custody in the early hours of Friday. After the court order around 2am, Rana was brought to the NIA headquarters on Lodhi Road and allowed to rest till the morning.

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