At least 19 Martin Luther King Jr.-Harbor Hospital employees will be fired and 45 others disciplined after a breakdown in vetting allowed scores of people with criminal records to remain on staff even after background checks indicated their past crimes, Los Angeles County officials said. The move to rid the staff of the most serious criminal offenders came as the interim director of the Department of Health Services acknowledged for the first time that failures by the human resources bureau overseeing the county's 17,000 health service workers may extend well beyond King-Harbor.