wrongful death

You might.  Many of the mental health services are provided via contract with private companies to the State of New Jersey.  Your ability to bring a suit depends on several issues, one of the first being the time that his death occurred.  If you are going to bring litigation against the State of New Jersey, you will need to file a Tort Claim notice within 90 days of the incident.  You can find a form on line, and you should send that notice by certified mail so that you have proof it was sent. If employees were negligent, and the negligence was the result of them not being trained properly, not having sufficient staff, etc. then it might give rise to a cause of action.