How did terror suspect David Headley get a visa to India? What documents did he provide to establish his identity?

Uncovering this will be tough since it's now official that Headley's papers have gone missing from the Indian Consulate in Chicago which granted Headley his visa. Foreign Secretary Nirupama Rao has written to the Consulate asking for an explanation.

The missing papers are the latest in a mystery that tends to get deeper and darker everyday. At the heart of India's concerns are suspicions that Headley was originally a CIA agent who switched sides and then planned the 26/11 attacks in Mumbai with the Lashkar-e-Toiba (LeT).

Headley, a US national who left Pakistan with his mother as a teenager, was arrested in Chicago by the FBI in October.

NDTV has reported extensively on whether Headley started out working for the Americans. These reports have been brought up in Parliament, with CPM MP Brinda Karat asking why America is not allowing India access to Headley. In a Chicago court, US prosecutors have charged Headley with plotting the 26/11 attacks as an undercover agent of the LeT.

Headley made multiple trips to India before 26/11. He allegedly took photographs and videos of the four sites that would later come under siege by Pakistani terrorists.

Indian sources are unhappy that despite these charges, Indian officials have not been allowed to meet Headley. America has also said that it's "too premature" to discuss Headley's possible extradition to India after his US trial is completed.

What's more worrying for India is that America's surveillance of Headley began in September last year, before the 26/11 attacks. Yet, no information on him was shared with India. America clearly had specific intelligence reports about the possibility of Mumbai hotels being targeted by terrorists - the Taj was mentioned in the warning passed onto India. But Headley did not figure in this alert.

Worse, India was not told about Headley even when he visited the country in March this year, supposedly to plan a new round of terror attacks. Instead, America waited till after Headley's arrest to share intelligence on him.

Sources say India suspects that Headley was enrolled as a spy after he was arrested for smuggling heroin in 1988. Did America then use him to infiltrate Pakistan's narcotics underworld? And did Headley use that as a cover to start working for Pakistani terrorists against India? Questions that now have India questioning whether America has shared everything it knows about a man named Daood Gilani who morphed into David Coleman Headley.