The board of directors of Highmark has terminated Kenneth R. Melani as president and chief executive. He had been on administration leave since March 29 after being arrested on March 25 for defiant trespass and simple assault. Since then, J. Robert Baum has been acting as CEO in addition to his role as board chairman, and will continue on an interim basis until a permanent successor is found. The Pittsburgh Business Times has put out three names of potential successors: Deborah Rice, division president of health services and executive vice president; Dan Onorato, head of government affairs and communications; and David Holmberg, the CEO of HVHC, HM Insurance Group and United Concordia Dental. Melani had headed up the company since January 2003.