The independent report presented to supervisors Tuesday reviewed nine cases in which children were killed or nearly killed and found "the mistakes of the past have been repeated."
Those mistakes included a failure to exercise proper judgment, follow procedure and communicate with other agencies involved in troubled families' lives.
Officials with the county's child protective services agency say they're implementing "multiple strategies" to address the mistakes.
In one case a child was murdered after being left with at least two unsafe caregivers.