"The Nixon led retreat... recovered most of POWs well before Siagons [sic] fall."
I'm reluctant to reply to you as you as it is not clear what you are contending and you also have a personal stake. So I found a couple of links:
Senate Select Committee Chronologies Part One: Vietnam War http://www.aiipowmia.com/ssc/vnchron.html
and
From http://www.pow-miafamilies.org/powmiastatistics.html
Accountability: : At the end of the Vietnam War, there reportedly were 2,583 unaccounted for American prisoners, missing or killed in action/body not recovered. As of October 19, 2004, 1,849 Americans are still so listed by the Defense Department, over 90% of them in Vietnam or in areas of Laos and Cambodia where Vietnamese forces operated during the war.
If you are hoping for closure on 1,849, the cruel fact is that you will be disappointed.