It is unclear what United States officials did with the warnings they had gotten about Mr. Headley, who has pleaded guilty to the crimes and is cooperating with authorities, or whether they saw them as complaints from wives whose motives might be colored by strained relations with their husband.

Federal officials say that the State Department and the F.B.I. investigated the warnings they received about Mr. Headley at the time, but that they could not confirm any connections between him and Lashkar-e-Taiba. D.E.A. officials have said they ended their association with him at the end of 2001, at least two months before Mr. Headley reportedly attended his first terrorist training. But some Indian officials say they suspect that Mr. Headley’s contacts with the American drug agency lasted much longer.

The investigative news organization ProPublica reported the 2005 warning from Mr. Headley’s American former wife on its Web site and in the Saturday issue of The Washington Post. By ProPublica’s account, she told the authorities that Mr. Headley boasted about working as an American informant while he trained with Lashkar.

On Saturday, Mike Hammer, a spokesman for the National Security Council, said in a statement, “The United States regularly provided threat information to Indian officials in 2008 before the attacks in Mumbai.” He also said, “Had we known about the timing and other specifics related to the Mumbai attacks, we would have immediately shared those details with the government of India.”

Mr. Headley’s American wife was not the only one to come forward. The Moroccan wife described her separate warnings in an interview with The New York Times. Interviews with United States and allied intelligence and security officials illustrate his longstanding connections to American law enforcement and the ISI:

¶ An officer of the Pakistani spy agency handed Mr. Headley $25,000 in early 2006 to open an office and set up a house in Mumbai to be used as a front during his scouting trips, according to Mr. Headley’s testimony to Indian investigators in Chicago in June. As part of Mr. Headley’s plea agreement, Indian investigators were allowed to interview him in Chicago, where he was arrested in October 2009. ¶ The ISI officer who gave Mr. Headley the cash, known as Major Iqbal, served as the supervisor of Lashkar’s planning, helping to arrange a communications system for the attack, and overseeing a model of the Taj Mahal Hotel, according to Mr. Headley’s testimony to the Indians.

¶ While working for Lashkar, which has close ties to the ISI, Mr. Headley was also enlisted by the Pakistani spy agency to recruit Indian agents to monitor Indian troop levels and movements, an American official said.