The FBI released this chilling footage of the Navy Yard shooter:
"Video footage from closed-circuit video cameras shows Aaron Alexis, now deceased, at the Washington Navy Yard on September 16, 2013," reads the FBI's description of the 30-second clip.
"The footage includes the following:
"- Alexis drives his rental car, a blue Toyota Prius, through the Washington Navy Yard main gate.
"- Alexis enters Building #197 carrying a backpack. Alexis had legitimate access to the Washington Navy Yard as a result of his work as a contractor and he utilized a valid pass to gain entry to the building.
"- Alexis moves through the hallways and a stairwell of Building #197 carrying a Remington 870 shotgun."