In almost every way, David Headley was the perfect neighbour. When the 49-year-old American citizen began renting an apartment in Mumbai last year he charmed his landlord, treated his laundry boy with respect, and befriended Bollywood figures at a local gym.
He told them that he was Jewish, and running an immigration agency from a respectable part of town. "Sweet and charming," said his landlady. "Down to earth," said his personal trainer.
Not until the past few days did they learn of his alleged other identity - and of quite how close security figures claim India may have come to a repeat of the militant attacks on Mumbai a year ago next week.
Apparently, Headley's original name was Daood Gilani. He was born in Pakistan, and is suspected of helping the terrorists who carried out last year's Mumbai attack, and of planning another atrocity this year.
The details emerged when the FBI arrested Headley in his home city of Chicago on October 3, and filed an affidavit in a US court, which has since been made public.
It alleges that he worked with Harkat ul-Jihad al-Islami, a Pakistan militant group, and Lashkar e-Taiba (LeT), the Pakistan group blamed for last year's Mumbai attacks. The document also outlines claims that he was involved in the "Mickey Mouse Project" - a plan to attack Jyllands-Posten, the Danish newspaper whose cartoons depicting the Prophet Muhammad in 2005 infuriated Muslims across the world.
It also allegedly shows that he and an apparent accomplice visited India several times between 2006 and this year, and appear to have discussed attacking Indian targets as recently as September this year.
Indian investigators are now examining whether Headley may be the "missing link" in the Mumbai attacks, which left more than 170 people dead between November 26 and 29 last year. They are also investigating claims that he may have planned attacks this year on targets including the National Defence College in Delhi, the private Doon School in Dehradun, northern India, or even a nuclear facility.
In the process, they are shedding light on the evolving threat from LeT and its allies, and on India's haphazard - but so far successful - efforts to respond. "This is yet another wake-up call for India," said B Raman, a former counter-terrorism chief in the Indian external intelligence service, the Research and Analysis Wing. "This shows LeT is as determined as ever to attack India, and they are now using Western territory and foreign Muslims to do it."
The most striking aspect of the Headley case is his profile: unlike other militant suspects, he is middle-aged, speaks fluent English, and lives in Chicago.
The son of a Pakistani diplomat and an American woman, he went to cadet college in Pakistan before moving to the US when he was 16. In 1997, he was jailed for 15 months for trying to smuggle heroin into the US, according to court documents.
Yet by simply changing his name in 2006, he stayed under the radar on at least nine visits to India over the past three years.
The FBI says that in the alleged activities he was helped by Tahawwur Hussain Rana, a Canadian citizen of Pakistani origin who studied at the same cadet college, and was also arrested in the US last month.
Kikr