The Tewksbury Board of Selectmen violated the Open Meeting Law in November by agreeing privately to credit sick days to a deputy police chief, and also by failing to announce the discussion as a reason for the closed-door meeting, District Attorney Martha Coakley’s office ruled, the Lowell Sun reports. In a five-page decision, Assistant District Attorney Heather Hall said the board broke the law in the manner in which it convened the Nov. 23, 2004, executive session and in holding the session for an improper purpose, the newspaper reports.