The gunman in Monday’s Navy Yard shooting in Washington D.C. was a subcontractor and former navy reservist who had a past record of gun violence.

Military records indicate that 34-year-old Aaron Alexis, who joined the Navy in 2007 and worked as an aviation electrician’s mate, received a general discharge from the service in January 2011 after a what military records indicate was a “pattern of misconduct”. He’d been involved in two minor shooting incidents in the past. In 2004, Alexis was arrested in Seattle for shooting out the tires of another man’s vehicle during what he told police was an “anger fueled blackout”. He’d apparently been upset with the parking situation at a construction site near his home. Workers alleged that Alexis had watched them for weeks before the incident. When questioned by police, Alexis claimed to suffer from post-traumatic stress following the September 11, 2001 terrorist attacks.

In 2010, while he was stationed in a naval air base in Forth Worth, Alexis was arrested for another gun related offense after a neighbor living in an apartment above his claimed she’d nearly been struck by a bullet fired through the ceiling of Alexis’ apartment. A police report stated that the woman was “terrified” of Alexis and that he’d confronted her in the parking lot about making too much noise. Alexis claimed the shot was fired accidentally while he cleaned his gun.

After being discharged, Alexis took a job with a professional services company subcontracted by Hewlett-Packard and was employed on a Navy IT project. His company ID badge allowed him access to the Washington D.C. Navy Yard where he killed 13 people Monday. Some cable news outlets had at one point speculated that there may have been multiple gunmen, but Washington Assistant FBI Director Valerie Parlave confirmed in a press conference yesterday that Alexis acted alone.