PHILADELPHIA -- The trip from a strict Pakistani boarding school to a bohemian bar in Philadelphia has defined David Headley's life, according to those who know the middle-age man at the center of a global terrorism investigation.

Raised by his father in Pakistan as a devout Muslim, Mr. Headley arrived back here at 17 to live with his American mother, a former socialite who ran a bar called the Khyber Pass.

Today, Mr. Headley is an Islamic fundamentalist who once liked to get high. He has a traditional Pakistani wife, who lives with their children in Chicago, but also an American girlfriend, a makeup artist in New York, according to a relative and friends. Depending on the setting, he alternates between the name he adopted in the United States, David Headley, and the Urdu one he was given at birth, Daood Gilani. Even his eyes -- one brown, the other green -- hint that he has roots in two places.

Mr. Headley, an American citizen, is accused of being the lead operative in a loose-knit group of militants plotting revenge against a Danish newspaper that published cartoons of the Prophet Muhammad. The indictment against him portrays a man who moved easily between different worlds. The profile that has emerged of him since his arrest, however, suggests that Mr. Headley felt pulled between two cultures and ultimately gravitated toward an extremist Islamic one.