The men were roommates in Philadelphia, and Young was moving to Phoenix. Early Thursday, Milledge, who works at Philadelphia International Airport, got a piece of his roommate's carry-on luggage to the boarding gate without going through security, the FBI said. Young, meanwhile, took a similar bag through security. The men switched bags at the gate - Young taking the one containing a 9mm pistol. Another passenger noticed the switch and raised concerns, and Flight 1195 was stopped and searched.