This announcement from DOD indicates they have now found enough evidence to declare him KIA.
In my role in Base Weather I briefed him on strike weather and refueling conditions and did the after action debriefs. I don't remember every pilot - but I do remember Capt White, soft spoken always polite to weather and intel briefers - we liked that. He was Capt at the time he was downed and promoted to Major during his KIA status.
His brother was Ed White one of the three Apollo Astronauts killed in the capsule fire during testing at the Cape in 1967.Their father was an Air Force Major General and that family lost both sons in service to the country.
Takhli Base Weather 69-70