The statements were recorded with the help of Federal Bureau of Investigation (FBI) and the United States Department of Justice over a period of nearly 10 days, official sources said, adding this is the first time that such cooperation took place between India and the US in the case.
Due to non-disclosure clause entered with FBI, NIA did not name the witnesses whose statements have been recorded but India had been pressing for questioning of wife of Pakistani-American Headley's wife Shahzia Gilani and other friends.
Headley, a 53-year-old Lashker-e-Taiba terrorist is at present undergoing 35 years of imprisonment on various counts including involvement in the conspiracy to carry out the audacious attack in Mumbai that left 166 people dead.
Besides Headley's wife Shazia, India had made request for questioning of Portia Peter and one more female friend and Tahawuur Rana, alleged to be an accomplice of Headley in the Mumbai terror strike.
The witness statements will help NIA to substantiate charges filed before a Delhi court in 2012 against top Lashkar-e-Taiba commanders alleged to have been involved in organising the 26/11 plot.
India had requested for statements of witnesses from the US in 2010 under a mutual legal assistance treaty but the process got stalled as America refused the presence of Indian investigators during the recording of the statements. The matter was resolved after discussions between the two sides.
India believes that Rana, Shazia and others have a lot of information and through their interrogations more light may be thrown on the conspiracy hatched to carry out the worst terrorist strike in India and role of those behind it.