Los Angeles County health officials have acknowledged that they had not used a key database intended to track and weed out problem employees from Martin Luther King Jr.-Harbor Hospital for nearly a year. John Schunhoff, interim Health Services Department director, told the Board of Supervisors that at least some employees had been fired or disciplined since the hospital closed its inpatient and emergency services in August. But since then, top managers have been unable to track the employees' locations and their subsequent performance and disciplinary status. The attention has coincided with a decision by Dist. Atty. Steve Cooley that no one would be prosecuted for the death of a patient last year who writhed untreated on the hospital's waiting room floor for 45 minutes.