The Los Angeles County Board of Supervisors is considering instituting a permanent, independent investigator to keep watch over the county's troubled hospital and clinic system. The proposal came a day after new disclosures about the level of incompetence among employees at Martin Luther King Jr.-Harbor Hospital. The investigator job was proposed by Supervisor Gloria Molina, who said trouble at the Los Angeles hospital developed in part because officials with the county Department of Health Services kept problems secret from the board.