WASHINGTON — An F.B.I. investigation into a member of a defense team for a Guantánamo Bay, Cuba, detainee accused of aiding the Sept. 11, 2001, terrorist attacks has been closed, a Justice Department official told a war-crimes court on Wednesday. The court filing is not yet public but was described by several people familiar with its contents.

Pretrial hearings in the prosecution of five detainees charged in the 2001 attacks were disrupted last month when defense lawyers complained that F.B.I. agents had interviewed a member of the defense team for Ramzi bin al-Shibh, one of the detainees, and asked him to sign a confidentiality agreement.

The judge overseeing the military commission tribunal, Col. James L. Pohl, appointed a special government review team, separate from the prosecution, to find out what was happening and report back. The review team filed a report that has not yet been made public on the tribunal docket because it is being reviewed for public disclosure, although it is not classified.

According to Brian Fallon, a Justice Department spokesman, the filing says the F.B.I. received information in November “that a nonattorney member of Bin al-Shibh’s defense team may have been involved in facilitating unauthorized communications with Bin al-Shibh and unknown individuals located abroad.”