New Delhi, Nov 19 (IANS) He could well have been discovered by John Le Carre. He came from Barack Obama's hometown, an Islamist at heart with a Christian name who claimed to be a Jew. His mission was to cause mayhem in India. As he remains in an American prison, Indian detectives are slowly uncovering David Coleman Headley's silent but vital role in the horrific Mumbai terror attack.

The Pakistan born American citizen was not alone in his mission. Along with childhood buddy and Canadian Tahawwur Hussain Rana -- also born in Pakistan -- he toured India extensively in the run up to the November 2008 Mumbai strike that left 166 Indians and foreigners dead in three days of naked terror.

Indian officials now say, privately, that Headley and Rana both reported to the same Pakistani jehadists who controlled the 10 male terrorists who sneaked into Mumbai a year ago and went on a slaughter spree.

It is now clear that it was Headley, looking every inch a middle class American, who lived in Mumbai for months to obviously sketch every site in the city that eventually came under attack from the terrorists.

The Lashkar-e-Taiba, the Pakistan-based terror group that is blamed for the Mumbai attack, could not have discovered a more loyal Islamist warrior than the 49-year-old from Chicago.

Now at the centre of an international probe by the National Investigation Agency (NIA) of India and the US Federal Bureau of Investigation (FBI), he is the first known case of the Lashkar drafting an American for terrorist attacks against India.

Headley, who apparently had no job, and Canadian businessman Rana have been accused of plotting terror attacks in India and Europe codenamed The Northern Project and Mickey Mouse respectively -- which the FBI feels had the blessings of the Al Qaeda.

On the radar was a Danish newspaper that had published cartoons of Prophet Mohammed, triggering riots across the Muslim world.

The Northern Project sought to hit India, where the two men travelled extensively and repeatedly. Between them, they visited half-a-dozen cities including Mumbai, Pune, Lucknow, New Delhi, Kochi, Ahmedabad and Jaipur.

Headley paid nine visits to India since 2006. He came to Delhi at least thrice and he was in Mumbai on two occasions. When 26/11 happened, Headley and Rana were presumably in Pakistan.

Because of his Christian sounding name and American passport, Headley found it easy to get across India.

Indian officials believe their arrest last month in the US foiled perhaps another carnage when India was preparing to mark the the first anniversary of the Mumbai attack.

'This arrest should open the eyes of the Indian security establishment of how big a threat India faces from Pakistan-based terror groups. An attack foiled and an individual arrested means a tragedy averted, not the threat,' Ajit Kumar Doval, a former Intelligence Bureau chief, told IANS.

Headley, who changed his name from Daood Gilani in 2006, was arrested Oct 3 at Chicago airport before boarding a flight to Philadelphia en route to Pakistan. Rana, 48, was arrested two weeks later from his home.

The FBI has charged Headley with conspiring to commit terrorist acts outside the US and supporting terrorism overseas. Rana has been accused of providing material support to a terrorist conspiracy.

Headley reportedly travelled extensively since the second half of 2008, including to Pakistan and India besides Europe. His strengths, it is said, were an eye for detail and a photographic memory.

Rana, owner of several businesses including First World Immigration Services, with offices in Chicago, New York and Toronto, allegedly helped arrange Headley's travels overseas.

'In July and August this year, Headley exchanged a series of e-mails with (an) Lashkar member... These e-mails reflect that LeT was placing a higher priority on using Headley to assist in planning a new attack in India,' the FBI affidavit said.

Between August and December 2008, Headley sent e-mail messages from Internet addresses in Karachi and Lahore in Pakistan. The FBI intercepted these.

'We need to establish conclusively if the two were indeed part of the 26/11 conspiracy,' said an investigator.