The two officials, speaking on condition of anonymity because they were not authorized to discuss the case, say Johnny Lee Wicks is the man who opened fire at a security checkpoint Monday morning and was shot dead in a gunfight with deputy U.S. marshals.
While the investigation is still under way, the officials say the early evidence points to the man's anger over his benefits case as the motive for the shooting.
Court records show Wicks had sued the Social Security Administration in 2008, but the case was thrown out and formally closed in September 2009.
Nicholas Gramenos, who had a jury summons and was near the courthouse, captured video and audio of the shooting on his cell phone:
Vegas shooting caught on tape