TIMELINE

Key events in Washington Navy Yard shooter Aaron Alexis’ military career, based on documents the Navy released Monday:

June 3, 2004 — About three years prior to his enlistment in the Navy Reserves, Alexis was arrested in Seattle and charged with malicious mischief for shooting the tires on a construction worker's vehicle. He remained in jail overnight and was released on his own recognizance. No charges were filed.

May 5, 2007 — Alexis enlisted in the Navy Reserve at the New York Military Entrance Processing Station in Brooklyn.

July 10, 2007 — Alexis graduated from recruit training at Great Lakes, Ill.

Aug. 4, 2007 — Office of Personnel Management closes its standard secret-level investigation of Alexis that started when he enlisted. OPM discovered his 2004 arrest and interviewed him about it, but its final report did not mention any firearms use. It said instead that Alexis had "deflated the tires on a construction worker's vehicle."

Dec. 15, 2007— Alexis graduated from Aviation Electrician's Mate "A" School and transferred to Fleet Logistics Support Squadron 46 in Atlanta. He remained with this squadron for his entire time in the Navy. The squadron relocated to Fort Worth, Texas, in 2009.

March 11, 2008 — A Navy review of the OPM investigation determined Alexis was eligible for a secret-level security clearance, with a single caution about his negative credit history. At the time, a secret clearance was good for 10 years.

Sept. 23, 2008 — Alexis received a non-judicial punishment for unauthorized absence that included forfeiture of half a day's pay per month for two months and a reduction of one pay grade. Both were suspended. Alexis was absent because he was in jail Aug. 10-11 in DeKalb County, Ga., following an arrest for disorderly conduct outside a nightclub. The incident stayed on his service record from that date forward.

July 12, 2009 — Alexis received a second non-judicial punishment for being drunk and disorderly and was reduced one pay grade. This NPJ was due to Alexis leaping off stairs and breaking his ankle while reportedly intoxicated. There was no police involvement. Alexis appealed.

Dec. 3, 2009 — Alexis' second NJP was set aside on appeal, based on a finding that there was insufficient evidence to prove he was intoxicated at the time of the incident. The report of NJP was removed from his record.

Sept. 5, 2010 — Alexis was arrested in Fort Worth for discharging a firearm in his residence the previous day. According to law enforcement documents, Alexis said he accidentally discharged the firearm while cleaning it. No charges were filed. After his arrest, Alexis' commanding officer initiated proceedings to administratively separate him from the Navy. But when Alexis was not charged for unlawfully discharging a firearm, the proceedings were halted.

Dec. 2, 2010 — Alexis requested separation from the Navy under a program that allowed sailors to request an early release.

Dec. 9, 2010 — Navy Personnel Command approved Alexis' request for separation.

Jan. 31, 2011 — Alexis received an honorable discharge, with the most favorable re-entry code.

Feb. 22, 2011 — Alexis was issued a Navy Reserve Identification and Privilege Card.

Sept. 16, 2013 — Alexis gunned down 12 workers in the nation's capital at the Washington Navy Yard, where he was working as an information technology contractor. He was killed in a police shootout.

A week after an IT contractor gunned down 12 workers at the Washington Navy Yard, Navy officials began moving to close gaps in the security clearance process, recommending that all police reports involving an individual must be included when a background check is done.

The Navy, in a report released Monday, revealed that the shooter, Aaron Alexis, did not disclose a 2004 arrest or some financial problems when he filled out his application for a security clearance when he joined the Navy as a reservist several years later. And officials said the background report given to the Navy at the time failed to reveal that Alexis had shot out the tires of another person’s car during a 2004 dispute in Seattle.

Instead, the report from the Office of Personnel Management, said Alexis “deflated” the tires, and did not mention the use of a gun.

Defense officials have acknowledged that a lot of red flags were missed in Alexis’ background, allowing him to maintain a secret security clearance and have access to a secure Navy facility despite a string of behavioral problems and brushes with the law. Over the past week, they have been struggling to determine what might have been missed, and what changes could be made in order to try to prevent similar violence in the future.

So far, however, the detailed reviews only underscore how subjective the security checks can be and how difficult it is to predict violent behavior based only on minor conduct issues that could easily be overlooked.

A review of Alexis’ nearly four-year Navy career, ordered last week by Navy Secretary Ray Mabus, revealed that the full scope of the 2004 arrest was not included in the security clearance report.

According to a senior Navy official, the police report included information about Alexis shooting out the tires of another man’s car, after a recurring dispute over parking. Alexis was arrested, charged with malicious mischief, fingerprinted and spent the night in jail. But when he appeared in court the charges were dismissed and he believed the incident was erased from his record.

The OPM report, provided to the Navy, described the incident in which Alexis deflated the man’s tires in retaliation for the man putting an unknown substance in Alexis’ gas tank.

The discrepancy prompted Mabus to recommend to Defense Secretary Chuck Hagel that all police reports — not just arrests — be included in a security check. He also recommended Monday that the Navy beef up its management of sailor evaluations and fitness reports by assigning more senior officers to oversee them.