In the frenzied days after Sept. 11, 2001, when some flights were still grounded, dozens of well-connected Saudis, including relatives of Osama bin Laden, managed to leave the United States on specially chartered flights. Newly released government records show previously undisclosed flights ... and point to a more active role by the Federal Bureau of Investigation in aiding some of the Saudis in their departure. The F.B.I. gave personal airport escorts to two prominent Saudi families who fled the United States, and several other Saudis were allowed to leave the country without first being interviewed. The material ... provides details about the F.B.I.'s interaction with at least 160 Saudis who were living in or visiting the United States and were allowed to leave the country. Some of the departing Saudis were related to Osama bin Laden. In several ... cases, Saudi travelers were not interviewed before departing the country, and F.B.I. officials sought to determine how what seemed to be lapses had occurred. From these documents, [the Saudi interviews that did occur] look like they were courtesy chats, without the time that would have been needed for thorough debriefings," said Christopher J. Farrell, who is ... a former counterintelligence interrogator for the Army. "It seems as if the F.B.I. was more interested in achieving diplomatic success than investigative success." The F.B.I. documents left open the possibility that some departing Saudis had information relevant to the Sept. 11 investigation.