2. Abu Zubaydah: A Palestinian caught in Pakistan last year after a shootout. He was reportedly a recruiter and operational planner.
3. Ramzi Binalshibh: A Yemeni also caught in Pakistan in September 2002. Supposed to have met Atta in a mosque in Germany in 1997.
4. Mohammed Haydar Zammar: A German citizen of Syrian descent, arrested in Morocco. Is believed to have recruited Atta.
5. Abd al-Rahim al-Nashiri: Chief of Al Qaeda operations in the Gulf. Suspected of organising the attack on USS Cole in Aden, Yemen. Caught last November.
In addition, more than 600 suspects remain in Guantanamo Bay, many of them handed over by Pakistan.