Aaron Alexis, the 34-year-old suspect killed in the U.S. Navy Yard shooting spree, had at least two earlier brushes with the law involving guns that led to the end of his four-year Navy career in 2011.

Mr. Alexis was a New York native who lived in Fort Worth, Texas, and worked in a Navy fleet logistics support squadron based there before he was discharged from the military after a 2010 arrest for firing a gun at his apartment. The incident sent a bullet into a neighbor's property a few days after an alleged confrontation with the neighbor over noise.

No one was injured and no charges were filed, according to the Tarrant County Criminal District Attorney's Office. According to the police report, Mr. Alexis said that "he was trying to clean his gun while cooking and that his hands were slippery."

A defense official said that Mr. Alexis was pushed out of the military following the apartment incident. "There is no question there was a pattern of misconduct," the official said.

In a 2004 incident in Seattle, police said Mr. Alexis had been arrested for shooting out the tires of another man's vehicle in an anger-fueled "blackout." Mr. Alexis told police at the time he had been deeply disturbed by events he witnessed during the terrorist attacks of Sept. 11, 2001. Police said Mr. Alexis's father said his son had been involved in 9/11 rescue efforts and had post-traumatic stress and anger-management issues.