Complex sentence: Such agencies operate on definitions of child abuse provided by the state's health department (which are often very different from the exceptions provided in the criminal code) and have the power to investigate cases with their own agents, such as social workers.
Split into simpler sentences: Such agencies operate on definitions of child abuse provided by the state's health department (which are often very different from the exceptions provided in the criminal code). Child protection agencies typically have the duty and authority to investigate cases with their own agents, such as social workers.