[dp_burke]

From ancestry.com, lists of those killed missing in Korean war:

Name:Ralph Donald MulhollenBirth Date:24 Feb 1918Birth City:FayettevilleState Registered:Tennessee Death Date:26 May 1951Death Country:KoreaDeath Description:Missing in Action - Presumed Dead War:Korean WarTitle:Captain, U.S. Air ForceRank:CaptainService:U.S. Air ForceService ID:AO1692664Notes:Captain Mulhollen was the pilot in a F-82 Twin Mustang night fighter with the 68th Fighter Interceptor Squadron, 6160th Air Base Wing. On May 26, 1951, while on a weather reconnaissance mission 20 miles north of the 38th parallel, contact was lost. He was listed as Missing in Action and was presumed dead on January 31, 1954. For his leadership and valor, Captain Mulhollen was awarded the Distinguished Flying Cross, the Air Medal with 3 Oak Leaf Clusters, the Purple Heart with Oak Leaf Cluster, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal and the Korean War Service Medal.Data Source:Korean War Veterans Honor Roll

and

Name:Arild Christian NielsenBirth Date:1 May 1922Birth City:MissoulaState Registered:Montana Death Date:26 May 1951Death Country:KoreaDeath Description:Missing in Action - Presumed Dead War:Korean WarTitle:Captain, U.S. Air ForceRank:CaptainService:U.S. Air ForceService ID:AO767341Notes:Captain Nielsen was the pilot in a F-82 Twin Mustang night fighter with the 68th Fighter Interceptor Squadron, 6160th Air Base Wing. On May 26, 1951, while on a weather reconnaissance mission 20 miles north of the 38th parallel, contact was lost. He was listed as Missing in Action and was presumed dead on January 31, 1954. Captain Nielsen was awarded the Air Medal with Oak Leaf Cluster, the Purple Heart, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal and the Korean War Service Medal.Data Source:Korean War Veterans Honor Roll

Did yo have the date wrong? There are no corresponding MIA for the 28th may 1951.