michae michael zehaf-bibeau, a convert to islam. he also went by another name, which was michael david hall. and we've learned there was another alias that he allegedly was using, abdullah zehaf-bibeau. he did try to travel outside the united states. we believe fairly recently, but wasn't allowed to because he was considered a high travel risk. his passport in effect seized. he said at the time he wanted to travel overseas to fight, according to one of our sources. however, a friend of his reportedly told the "globe and mail" that he had run into the gunman just a few weeks ago and was told that he intended to go overseas to study islam. at this hour, rosemary, some additional information. there is a strong police presence outside the home of the gunman's mother which is believed to be her home. police are guarding that location at this time in montreal. >> earlier we understand, authorities thought there was another shooter at large. now they've ruled that out. how can they be so sure there was only one gunman involved? how do they rule out the possibility of a second one? >> well, certainl