"Even before the crisis ended, the investigation had begun," FBI Director Robert Muller said while delivering a speech on FBI's role in global terrorism at the Council on Foreign Relations.

"Agents from FBI offices in New Delhi and Islamabad joined forces with Indian government, the CIA, the State Department, MI-6 and New Scotland Yard," he said.

Through these partnerships, Muller said: "We had unprecedented access to evidence and intelligence. Agents and analysts conducted more than 60 interviews, including that of the lone surviving attacker.

Our forensic specialists pulled fingerprints and DNA from improvised explosive devices," he said. FBI agents recovered data from damaged cell phones and in one case by literally wiring a smashed phone back together.

"At the same time, we collected, analysed, and disseminated intelligence to our partners at home and abroad, not only to determine how these attacks were planned and by whom, but to ensure that if a second wave of attacks was in the offing, we possessed the intelligence to stop it. Our work in Mumbai was not out of the ordinary," he said.

"To counter these (terror) threats, we must first understand them through intelligence. And once we gain an understanding, our law enforcement authorities allow us to move against individuals and networks," Muller said.

He also praised the FBI agent in New Delhi who took a lead role in investigating the Mumbai attack.

"The day before the attacks in Mumbai, Special Agent Steve Merrill - our legal attaché in the FBI's New Delhi office - was enjoying his first day off in nearly a month," he said.

"He (Merrill) was on his way to Jodhpur (Rajasthan) to play cricket on the US embassy team in the Maharajah's annual tournament. For the record, you do not need to know how to play cricket to work in the FBI's New Delhi Office, but it certainly does not hurt," Murrell said amidst laughter.

"The moment he learned of the attacks, Steve made his way to Mumbai," he said, adding Merrill immediately made contact with his Indian counterparts and got to work.

"No red tape, no turf battles; just first responders working shoulder to shoulder in a time of crisis," he said.