It was not immediately clear whether al-Libi had been involved with al-Qaida since or had been connected to militant activities in Libya, where al-Qaida has a growing presence since Gadhafi's was unseated.
His family denied he was ever a member of al-Qaida and said he was not involved in militant activity since his return.
In a 157-page indictment filed in the Southern District of New York in November 1998, the U.S. government accused al-Libi and others of conspiring to kill American civilians and military members at the embassies in Kenya and Tanzania.
Specifically, prosecutors said al-Libi helped bin Laden and al-Qaida plan the attacks on the U.S. Embassy in Nairobi by scouting and photographing the site in 1993. The indictment also alleges al-Libi discussed other attacks on the U.S. Agency for International Development as well as British, French and Israeli targets in Kenya.
The court filing does not charge al-Libi in the bombing and deaths of those at the embassies, but rather says he conspired to achieve that result.
Associated Press writers Philip Elliott and Donna Cassata in Washington, Kimberly Dozier in Charlotte, N.C., and Matthew Lee in Bali, Indonesia, contributed to this report.