No confirmation of this, NBC just reported it.
This appears to be him, the name, age and place match up (note: this is from 2010).
. . . According to the reports, Alexis is a Ft. Worth, Texas, native who recently worked as a civilian contractor in Washington, D.C. An arrest record from Tarrant County in September 2010 shows he was arrested for discharging his weapon.
As NBC reports, a neighbor called police “after hearing a bullet rip through her floor and ceiling. he told police he had been cleaning the weapon when it slipped and accidentally pulled the trigger. they filed the police with the district attorney’s office but charges were never filed.”