One of the guns used by Mateen at the Pulse nightclub was an AR-15 semiautomatic rifle. The gun was also used in the massacres at Sandy Hook Elementary School; the Aurora, Colorado, movie theater; and at the Inland Regional Center in San Bernardino, California. AR-15-style rifles like Mateen’s were once illegal under the federal assault weapons ban, which expired in 2004. Trevor Velinor of the Bureau of Alcohol, Tobacco and Firearms said Mateen purchased his guns legally.

Trevor Velinor: “Yes, ATF has traced those firearms. We know that this individual did purchase at least two firearms. He is not a prohibited person, so he can legally walk into a gun dealership and acquire and purchase firearms. He did so, and he did so within the last week or so. And thus far, we’re following up on that, so I’m not going to get into the detail as to the specific location of the purchase. But he did purchase two firearms—a handgun and a long gun—within the last few days.”