Naturalized US citizen lost original Chinese passport. What can I do to get Chinese visa?

My Dad was born in Macau (formerly Chinese nationality) but is now naturalized US citizen. He no longer has his original Chinese passport (which is a requirement for Chinese visa) and does not have any copies of it. We have searched everywhere. This is the first time he is applying for a Chinese visa since coming to US 30+ years ago. Since he was not born in mainland China, I am hoping we can show other documents in place of the original Chinese passport?? Any help/suggestions would be appreciated.