Veteran defensive back Kevin Mathis, who missed the final two months of the 2006 season with the second serious neck injury of his career, was released on Monday by the Falcons in a move that had been anticipated. It is not yet known if Mathis will attempt to continue his career with another team. Sources said he would have had trouble passing his physical examination with the Falcons, who begin a mandatory, three-day minicamp on Tuesday morning.