Officials report that Aaron Alexis, identified as the gunman in the Washington D.C. Navy Yard Shooting, was armed with a shotgun and two handguns.
Before Monday’s shooting, Alexis previously had two gun-related incidents but neither resulted in charges against him. The first, in Seattle in 2004, involved Alexis shooting out the tires of another invidiual's car. The second, in Fort Worth in 2010, saw Alexis shooting through his floor into the apartment below. During both, reports say that Alexis appeared to be spurred by anger. The Seattle incident was reportedly fueled by Alexis' displeasure with construction workers parking their cars near Alexis' home. According to his downstairs neighbor in Fort Worth, Alexis had repeatedly called the police on her for making too much noise.
According to Michael Ritrovato, a former roommate of Alexis', Alexis had recently felt frustrated with, and owed money by, the company he worked for as a Navy contractor.
A direct motive for the shooting is still unclear, and is likely to remain so for some time.
The F.B.I. is still searching for a possible second suspect, but according to Pete Williams for NBC, the likelihood of another individual involved is "rapidly" decreasing. The investigation remains open and active.