Ms. Christie, 61, said by telephone that receiving Lieutenant Kelly’s remains would provide even more closure for her family. She has now read all of the letters he wrote home during the war, she said, and his grave in Livermore, Calif., has recently taken on new significance for her.

To honor Lieutenant Kelly and the other crew members, a B-24 bomber flew over the cemetery three times on Sunday. A 21-gun salute and flag-presentation ceremony were also held.

“It was wonderful,” Ms. Christie said.

In his correspondence, the young bombardier’s tone is often optimistic, even as he acknowledges the hardships and dangers of his assignment. In one letter, he digresses to say he took a break from writing to eat a quart of ice cream.

Ms. Christie said she was struck by how very young her uncle had been, and by his constant concern for how his family was dealing with his absence.

“If we are lucky we might get home by next Christmas, but it’s hard to say for sure,” Lieutenant Kelly wrote on Feb. 1, 1944, shortly after his 21st birthday.

“How are Mom and Dad?” he wrote on Feb. 29, less than two weeks before he died aboard Heaven Can Wait. “Are they doing a lot of needless worrying?”