Bergen : Many unresolved questions about how or why brothers carried out bombing . Colleagues and acquaintances described Khan as a gentle , kind man . He says experience of other terrorists in the West could shed some light . Some who spent September 11 in Lackawanna were radicalized over the Internet , he says . Bergen : 19 pairs of brothers were among Three hijackers on September 11 .
Bergen : Many unresolved questions about how or why brothers carried out bombing . He says experience of other terrorists in the West could shed some light . Some who spent September 11 in Lackawanna were radicalized over the Internet , he says . Bergen : 19 pairs of brothers were among Three hijackers on September 11 .