What we know: Federal law enforcement sources say authorities have recovered three weapons from the scene of the mass shooting, including one -- a shotgun -- that investigators believe he brought in to the compound. The other two weapons -- handguns -- the sources say, may have been taken from guards.
What we don't know: The sources, who have detailed knowledge of the investigation, cautioned that initial investigation information that an AR-15 rifle was used may have been incorrect. It is believed that Alexis had rented an AR-15, but returned it before Monday morning's shootings.
On Sunday, Alexis purchased a Remington 870 shotgun and a small amount of ammunition at Sharpshooters Small Arms Range in northern Virginia, the store's attorney, J. Michael Slocum, said. Alexis spent "a couple hours" there, including at its practice range, the lawyer added. In according with federal law, Alexis name and other applicable information was provided to the National Instant Criminal Background Check System and he was approved to purchase the gun, according to Slocum.
Alexis had the proper credentials to get into the Navy Yard, said Washington's mayor. But Gray added that it was unclear how he got the shotgun past security.
Parlave, from the FBI, said Tuesday that Alexis may have gotten hold of the handguns after he got into the military facility.
What we know: The incident will certainly rev up the often explosive debate over gun control. But initial reports show Alexis obtained his primary weapon legally.
What we don't know: Will the shooting at Navy Yard change the political landscape? High-profile shootings over the last several years have done little to move the needle in Washington. President Barack Obama pushed for universal background checks and other directives after the the Newtown, Connecticut, shootings, to cut down on the access Americans would have to firearms, but they never gained traction. At the state level, it's been a similar story. The successful recall elections last week of two Colorado lawmakers who backed new gun restrictions sent a shiver through the gun control lobby.