Check your CPS's website to see if they are being attacked with phishing and/or phone scams as they might have something. We can't really comment here as different jurisdictions will have differing rules/methodologies.
If their website isn't forthcoming, then call CPS and ask if they would ever inform anyone in such a manner. I suspect the answer is no but it's better to make sure. I suspect your father would be informed in writing but do double check.