Friday afternoon, one of his sons dropped him off in Flushing to have pictures taken, and he has yet to return.
The family has searched throughout Flushing and has been searching local train stations.
The NYPD, Port Authority Police and hospitals have all been contacted, but so far, there is no sign of Sang.
He is said to speak Cantonese and Spanish.
If you have any information please contact the police as soon as possible.