Aaron Alexis, 34
Aaron Alexis, 34Facebook

Aaron Alexis, the 34-year-old gunman who killed 12 in Monday's shooting rampage at the U.S. Navy Yard in Washington, was previously arrested twice for gun related offences and suffered from post traumatic stress disorder (PTSD) and anger fueled "blackouts".

According to a report by The Guardian, Alexis was a former reservist who was arrested twice in the past for gun-related offences and was discharged from the navy in 2011 after an incident in which an upstairs neighbor complained that he had shot into the floor of her apartment. 

But Alexis restored his connections with the navy when a professional services company subcontracted by Hewlett-Packard employed him on a navy IT project. His ID badge gained him access to the navy yard base on Monday, the FBI said.

HP said in a statement the contract was "to refresh equipment used on the Navy Marine Corps Intranet (NMCI) network,” adding it was “cooperating fully with law enforcement as requested.”

Checkered Past

According to the US navy, Alexis, whose home was listed as New York City, enrolled in the reserves in 2007. He was a navy aviation electrician from February 1, 2008, until he was discharged on January 31, 2011. He is listed as having received the national defense service medal and the global war on terrorism service medal.

While based at Fort Worth in Texas in 2011, Alexis was arrested after discharging a firearm. In 2004, police in Seattle questioned him after what they described as an "anger-fuelled shooting" involving the car of a construction worker.

Seattle police said on Monday that during their inquiries into the 2004 incident, Alexis's father reported that he suffered from "anger management problems associated with PTSD, and that Alexis had been an active participant in rescue attempts on September 11, 2001".

The statement went on: "Following his arrest, Alexis told detectives he perceived he had been 'mocked' by construction workers the morning of the incident, and said they had 'disrespected him'. Alexis also claimed he had an anger-fueled 'blackout' and could not remember firing his gun at the victims' vehicle until an hour after the incident."

In April 2010, Alexis was arrested for discharging a firearm in an apartment, according to a Fort Worth Police Department incident report. He claimed the weapon went off accidentally when he was cleaning it.

Meanwhile, a soon-to-be released government audit is said to note how the Navy let down its guard to risks posed by outside contractors at the Washington Navy Yard and other facilities in an attempt to reduce costs. The audit, commissioned before Monday's tragic events, shows a history of those with criminal records managing to bypass the Navy’s security.

Fifty-two “convicted felons received routine unauthorized installation access, placing military personnel, attendants, civilians in installations at an increased security risk,” according to the report.