From:
https://en.wikipedia.org/wiki/Richard_Evelyn_Byrd_III
Death
He died on or about October 3, 1988, at the age of 68. His body was found in a warehouse in Baltimore, Maryland. He had gone missing on September 13, 1988, after being placed on a train in Boston bound for Washington, D.C. Byrd was supposed to attend a
National Geographic Society event honoring the 100th anniversary of his father's birth, but never arrived.
[2]
The cause of his death was dehydration and malnutrition which resulted from
Alzheimer's disease.
[3]
He was buried, near his father, in
Arlington National Cemetery.
[1][4]