Three weeks after the Marine Corps called off a search for three Marines lost when an MV-22 Osprey crashed in waters off the east coast of Australia, officials said the remains of all three have been recovered and are on their way home.

Killed in the Aug. 5 tragedy were 1st Lt. Benjamin Cross, 26, of Oxford, Maine; Cpl. Nathaniel Ordway, 21, of Sedgwick, Kansas; and Pfc. Ruben Velasco, 19, of Los Angeles. Cross and Ordway were both assigned to Marine Medium Tiltrotor Squadron 265 out of Futenma, Japan; Velasco was a member of 3rd Battalion, 5th Marines, out of Camp Pendleton, California.

Officials with III Marine Expeditionary Force said early Friday that Cross had been posthumously promoted to captain and Velasco to lance corporal.

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The remains of Cross were most recently recovered and are awaiting transfer to Hickam Air Force Base, Hawaii, officials said. Those of Ordway and Velasco are already at the base. From there, they will be sent to a point designated by the families of the fallen for funerary honors.

"A solemn, dignified transfer of remains continued to be the priority as our fallen Marines are returned to their families," officials said in a statement.

A search-and-rescue effort for the missing Marines spanned about 12 hours. The V-22, which belonged to VMM-265, the air combat element of the 13th Marine Expeditionary Unit, apparently crashed into the water shortly after launching from the amphibious assault ship Bonhomme Richard. It's still not clear why the aircraft crashed, and the incident is being investigated.

This year is the deadliest for Marine Corps aviation in years. The tragedy near Australia closely follows the July 10 crash of a KC-130T transport aircraft in Mississippi that resulted in the deaths of the 15 Marines and one sailor aboard.

In the wake of that tragedy, the Marine Corps grounded all KC-130Ts remaining in the fleet; they still remain grounded.

On Aug. 11, Marine Corps Commandant Gen. Robert Neller announced that all Marine Corps aviation units would observe a 24-hour "operational reset" grounding period within the next two weeks to review safety procedures and identify possible problems.

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.