widening, and triggering questions of a very culture of a special organization. we begin tonight with kristen welker who accompanied the president to colombia and back. kristen, good evening. reporter: good evening, brian. investigators, the pentagon and secret service are trying to find out how this could have happened. all 11 secret service personnel have had their security clearances pulled. according to u.s. officials, at least 11 secret service and more than five military personnel are involved in the widening prostitution scandal. nbc's national investigative correspondent mike isikoff has been working the story. >> sources tell us, among those involved, were two secret service advisers, three members of the counter sniper team and three members of the counter assault team were among those involved. >> reporter: isikoff says investigators are looking into the possibility that more may be involved. >> we're told all of those involved had hard copies of the president's day by day, minute by minute schedule. and if the prostitutes had access to that, they could have potentially given it to a foreign intelligence service, drug cartel or even a terrorist group. reporter: it happened last wednesday nig