Mr. Wynne would not comment on detention policies, and said that he should not be "held out as the one lone person who did the right thing." But during an extended interview approved by his F.B.I. superiors, he read aloud from phone logs documenting desperate messages from the man's family in Katmandu, his efforts to reassure the weeping detainee, and his own dawning recognition that no resolution was in sight. "I told Purna that I would try to help him, that I wouldn't forget about him," Mr. Wynne explained. "I felt some - not responsibility, but I felt that there was no one else." By telephone from Katmandu, Mr. Bajracharya recalled the fear, humiliation and despair he had experienced in prison. "I had nothing but tears in my eyes," he said through a translator. "The only thing I knew, I was innocent, but I didn't know what was happening." He said he was stripped naked in the federal jail. "I was manhandled and treated badly," he said, becoming agitated. "I was very, very embarrassed even to look around, because I was naked." The ordeal began when his videotaping aroused the suspicions of two detectives from the Queens district attorney's office, which has space in the same 12-story building where the F.B.I. occupies three floors. After taking him inside for questioning, they called upstairs to the F.B.I., and Mr. Wynne was dispatched to take over the interrogation. With no translator, Mr. Bajracharya tried to explain himself to half a dozen law enforcement officers, including two federal agents from the Immigration and Naturalization Service who verified his illegal immigration status. It was Mr. Wynne, as the lead F.B.I. agent, who sent him to the federal detention center in Brooklyn pending a thorough investigation. The F.B.I. agent, now 50, describes himself as a lifelong New Yorker who does not take illegal immigration lightly. His specialty is international art fraud, not terrorism. But at a time of heightened anxiety about another terrorist attack, he maintained, it was reasonable to suspect the worst until he could check the man's history, discrepancies in his identity documents and questions about money wired to Nepal. The questions were resolved within days. The Nepalese man did not show up in any terrorist databanks, and Mr. Wynne soon confirmed his explanation for a $37,000 wire transfer to Nepal. The money was from a recent legal settlement for injuries suffered when he was hit by a car in 1999. His records, roommates and former employees all vouched for the detainee's honesty. On Nov. 1, 2001, the day Mr. Wynne wrote his report clearing Mr. Bajracharya, he told him through a translator that it would take about a week to get the matter resolved. Over the weekend, pleading messages arrived from the detainee's sons in Katmandu: "Please help his father; he's not that kind of person - meaning a terrorist, I suppose," the F.B.I. agent said. On Nov. 5, he discussed the case with the head of counterterrorism in the United States attorney's office, and on Nov. 7 and 8, with a lawyer at the immigration agency. "Because he was willing to leave - he wanted to leave - it didn't seem to me that it was a big hurdle to move him out of there," Mr. Wynne said. But the weeks dragged on. Learning that a secret immigration hearing was scheduled for Nov. 19, Mr. Wynne thought a resolution was at hand. Instead, in a second conference call to the detainee after the hearing, he found him confused and distraught. It turned out that official F.B.I. clearance from Washington had not yet come through, and the matter had been adjourned to another secret hearing on Dec. 6. At this point, the agent said, he realized he had been too optimistic. "You have to understand one thing: I'm in the Queens office; in Manhattan they were running this whole initiative, and there was a whole procedure set up for the clearances," he said. "I wasn't aware that there were so many levels that needed to sign off on this thing, frankly, when I filed my report." The Monday after Thanksgiving, the F.B.I. agent called in Legal Aid. "This guy needed some help - it's as simple as that," Mr. Wynne said, insisting that anyone would have done the same thing. Ms. Cassin says she knows of no other F.B.I. investigator who has. But by the time she spoke with the detainee, through a thick plexiglass barrier and under the eye of a prison video camera, she said, he was weeping all the time.