The remains of four U.S. servicemen killed in the Vietnam War 38 years ago have been identified and returned to the United States for burial, the Pentagon said on Monday.

They were named as Marine 2nd Lt. Heinz Ahlmeyer Jr. of Pearl River, N.Y.; Marine Sgt. James Tycz of Milwaukee, Wis.; Marine Lance Cpl. Samuel Sharp Jr. of San Jose, Calif., and Navy Petty Officer 3rd Class Malcolm Miller of Tampa.

Ahlmeyer, Tycz, and Miller will be buried in Arlington National Cemetery on May 10. Sharp was buried Saturday in San Jose and will be honored at the Arlington ceremony.

The four were part of a reconnaissance patrol operating near the U.S. Marine base in Khe Sanh in Quang Tri Province, South Vietnam which came under attack shortly after midnight on May 10, 1967. The four were killed.

The patrol’s surviving members were rescued by helicopter but the bodies of the dead could not be recovered.

Between 1993 and 2004, eight joint U.S.-Vietnamese teams interviewed witnesses and surveyed the area. Two other teams conducted excavations, recovering evidence and remains, and after analysis the remains of the four were identified.

There are still 1,835 U.S. troops missing from the Vietnam War and 748 Americans have been accounted for.