To make the tale even more dramatic, Headley may just have provided American intelligence agencies information that prevented a Lashkar attack on Mumbai in September. The theory -- and it′s still a theory -- is that Headley was used to infiltrate the Lashkar, but gradually went astray under the influence of the very terrorists he was supposed to be spying upon.

Torn between conflicting loyalties, he may have continued to give information to his American handlers, and a tip-off by him may even have helped avert a Laskar attack orginally planned for September. But he seems to have commited fully to Lashkar shortly after that, which could be one reason why American agencies were caught napping by 26/11.

During his interactions in India, Headley frequently introduced himself as a CIA agent. But suspicions that he′s a rogue agent stem more from the just-released information that Headley, a man with one green and one brown eye, could straddle America and Pakistan with ease despite a run-in with the law in the US

A recent profile in the New York Times said that in 1998, Headley (then known as Daood Gilani) was convicted of conspiring to smuggle heroin into US from Pakistan. ``Court records show that after his arrest, he provided so much information about his own involvement with drug trafficking which stretched back more than a decade and about his Pakistani suppliers that he was sentenced to less than two years in jail and later went to Pakistan to conduct undercover surveillance operations for the Drug Enforcement Administration (DEA)," the NYT report said.

This suggests that Headley had a deal with authorities in the US who allowed him to get away with mild punishment in exchange for a promise of cooperation.

To many here, that also implies that he was a known entity to the counter-terror and drug enforcement authorities in the US. After 9/11, the walls between these agencies had come down because of the links between drugs and terrorism, particularly in the context of Pakistan-Afghanistan where there is a huge overlap between the functions of the DEA and CIA. Surprisingly, the FBI affidavit against Headley doesn′t mention his tryst with the DEA.

FBI′s affidavit against Headley says that he changed his name from Daood Gilani to David Coleman Headley in 2006 to hide his history as an offender. As he told border police in August 2009, it was to give himself the freedom to travel undetected -- he said the new name aroused much less suspicion when he travelled.

It is a fact that terrorists are masking their religious identity to get past the counter-terror surveillance, with terror groups seeking to recruit Caucasians for fresh strikes. But many doubt here that the mere switching of names could have worked in Headley′s case given his brush with law but more because of the destinations he was flying to.

Given Pakistan′s unquestioned reputation as the hub of global terror, people travelling to and from the country automatically pop up on the scanner at airports across the globe. Headley, to boot, would often meet his contacts in UAE -- a known rezendevous for terrorists and smugglers and a place that is of immense interest to law enforcement agencies.

The doubters found it intriguing that ultra-sensitive agencies in the US did not find anything amiss about the entries on Headley′s US passport. While the sceptics don′t think they have an answer yet, they are inclined to look at the possibility of Headley being an undercover agent who, torn between the competing demands of the jihadi outfits he had been asked to infiltrate and his American handlers, went astray.

Headley, by his own confession, joined Lashkar-e-Taiba in 2006 and received training in one of the terror camps run by the jihadi outfit.

Those who subscribe to the "rogue agent" theory are inclined to believe that this was known to the Americans, always anxious to ferret out information from hard-to-penetrate terror groups. They also feel that US agencies were perhaps aware that last year, Headley was in India to recce targets for a Lashkar attack that it had originally planned for September -- as confirmed by Ajbal Kasab in his testimony -- and which was finally carried out on 26/11. Rather, they also suspect that Headley might have been the source of information that helped Americans warn of the attack planned for September last year.

In their warning, which was passed on to Maharashtra government by Intelligence Bureau, the Americans had said that prominent installations in Mumbai were on the jihadis′ target. As a matter of fact, the FBI alert made a specific mention of Taj and other hotels -- Marriott, Land′s End and Sea Rock.

It is felt that Headley′s defection happened immediately afterwards and that is perhaps one of the reasons why Americans could not, unlike in September, sniff 26/11. The suspicion is reinforced by the fact that it was around this time that FBI put Headley under its surveillance, leading to his arrest on October 3 this year.

Suspicions are getting stronger as Americans delay giving Indian investigators access to Headley. The hope here is that Indian agencies would get their turn to talk to the terrorist after charges -- indictment in the American lexicon -- are framed against him on Jauuary 1. There is also the possibility that Headley has promised to sing on the condition that he is not exposed to interrogators from India.

But during interactions on the issue, FBI has been unusually cagey about discussing Headley in detail -- odd on the part of the agency which swiftly warned of the attack Lashkar had planned in September and without whose help the breakthrough in the 26/11 probe would not have happened.