The American POWs are dead. We have been recovering many remains as of late. I feel bad for you if your family member was not recovered yet, and all my sympathy is with those who have yet to recover a loved one from SE Asia. Nevertheless, the probability that American POWs are still alive in Nam is slim to none.
I refer you to, “POW/MIA’s - Report of the Select Committee on POW/MIA Affairs United States Senate, January 13, 1993 -Ordered to be printed. Filed pursuant to Senate Resolution 10. 103d Congress 1st Session, Report 103-1.” It has an olive green cover. Also, the hearings were on CSPAN.
Our people, military and civilian were not only held in S/E Asia (Vietnam, Laos, Cambodia) but also taken to the Soviet Union, see pps. 426 and 427 among others.