The body of Lt. Cmdr. Albert A. Schaufelberger III, killed in El Salvador, arrived at Oceana Naval Air Station in Virginia Beach late yesterday afternoon after a memorial service in San Salvador, where he was eulogized as a martyr for the cause of "peace and liberty in the world."

Schaufelberger, 33, was shot three times in the head Wednesday as he sat in his parked car on the campus of the Jesuit-run Central American University in El Salvador.

After the camouflaged C130 rolled to a stop at Oceana, the rear doors of the plane dropped open, a five-person Navy color guard marched in and came out with Schaufelberger's flag-draped coffin.

In El Salvador, Ambassador Deane R. Hinton, who accompanied the body to the plane at Ilopango air base and saluted as it was carried aboard, said Salvadoran police have begun an investigation of the death and will likely get FBI help in solving what he called Schaufelberger's "shocking, cowardly murder."

Salvadoran leftist guerrillas claimed responsibility Friday for Schaufelberger's death.

Radio Farabundo Marti, the voice of the Popular Liberation Front, said Schaufelberger was "executed" by the Clara Elizabeth Ramirez commando as a warning against U.S. intervention in El Salvador's civil war. Salvadoran investigators said the assassins had used explosive bullets.

The FPL is El Salvador's oldest and most hard-line leftist guerrilla movement. It is grouped together with four other insurgent organizations under the umbrella Farabundo Marti National Liberation Front (FMLN), which is battling to overthrow El Salvador's U.S.-backed government.

The Ramirez commando takes its name from a woman guerrilla killed in a clash with government troops.

Schaufelberger, of San Diego, was deputy commander of about 50 American advisers training Salvadoran armed forces against leftist guerrillas.

The Salvadoran high command yesterday joined U.S. officials at an hour-long memorial service for Schaufelberger at the Union Unitarian Church in San Salvador. "Albert must have known that any action that has significance can bring on one's death," said the Rev. C. Edward Ward of Dallas, pastor of the church.

Col. John D. Waghelstein, commander of the U.S. military group, his voice shaking, paraphrased a Jewish proverb that he said his father related when he lost a brother: "A good person's name can last forever."

"Al Schaufelberger, your friends and family have to leave you at the gate, but your good name precedes you. God speed, my friend," Waghelstein said.

A 12-man U.S. Marine Corps honor guard in dress uniform carried Schaufelberger's coffin to a waiting hearse as Salvadoran and U.S. officials stood at attention along the walk out of the church. A short time later, 200 Salvadoran paratroopers lined the airport tarmac as Hinton, Waghelstein and seven American advisers escorted the coffin on a trolley. A Salvadoran national guard band played a funeral dirge.

One American adviser said yesterday that Schaufelberger "was an easy target" because he visited the university several times a week, at about the same time in the evening. Schaufelberger was meeting a 34-year-old Salvadoran woman friend when he was shot.

The Associated Press said the shooting occurred after dark when the street was crowded with vehicles and students leaving class. Four men pulled alongside Schaufelberger's green Chevrolet Malibu, a U.S. government vehicle.

One of the men aimed a revolver through an open window and fired four times. Witnesses, all of whom asked not to be named, said that the assailants wore civilian clothing and that at least two had submachine guns.

Schaufelberger's body is to be flown today to Charleston, S.C., and taken by hearse to Beaufort, S.C. His father, retired Capt. Albert Schaufelberger, and his mother live in Fripp Island, S.C.