text:  There are two key pieces of evidence that they have recovered that they're working on, the alleged shooter's gun and his cell phone. Both have been sent to the FBI lab in Quantico, Virginia, for analysis. The FBI says the gun was purchased legally, it believes, by the shooter's father. Rojek identified it as an AR-556, which is an AR-15-style rifle. The cell phone, though, is an urgent focus for investigators.