1.   It may be possible to show that bin Laden knew the perpetrators, but the paper trail is unlikely to reveal more than that.

2.   In the interview with the Arabic daily Al-Hayat, Yousef also suggested he knew the perpetrator and supported the group that carried out the attack.

3.   In the interview in the Arabic daily Al-Hayat, Yousef also suggested he knew the perpetrator.

4.   The perpetrators were not known, he added.