Philippine President Ferdinand Marcos appointed a fact-finding commission composed of five judges today to investigate the slaying Sunday of his longtime political rival, Benigno Aquino Jr.

The membership is not likely to satisfy members of the Aquino family and opposition politicians, who have said they hoped for selection of nongovernmental figures and experts approved by the family.

A statement from Malacanang Palace, the presidential residence, said the commission would make "a free, unlimited and exhaustive investigation into all aspects of the tragedy" and report its findings directly to the president.

Aquino, 50, was shot to death as he stepped off an airplane at Manila's international airport. The government has said that a lone--and still unidentified--gunman shot him in the back of the head. The slayer was promptly killed by airport security men, the government has said.

A persistent political critic of Marcos, Aquino had spent three years in self-imposed exile in the United States and was returning here in an attempt to continue his opposition.

Almost no evidence surrounding the killing has been made public yet, and the police have said they are still unable to identify the gunman.

Some members of the opposition United Nationalist Democratic Organization have questioned the government's ability to make an impartial investigation of the assassination and have said the choice of investigators should be made with the approval of Aquino's family.

The chairman of the commission appointed today is Chief Justice Enrique Fernando. It includes a former chief justice, Roberto Concepcion, and three current members of the Supreme Court. All generally are regarded here as friendly to the president and are not known as dissenters in cases involving his government's policy.

The statement said Marcos is offering a reward of 500,000 pesos (about $46,000) for any information leading to the arrest of others involved in the shooting.

Marcos said in a television interview Monday night that the killer may have had accomplices, and several observers have said they considered it improbable that a lone man could have gotten close enough to Aquino to shoot him in the head without assistance from others. The scene of the shooting was guarded closely by airport security officers at the time.

Marcos also ordered all members of the airport security force confined to quarters during the commission's investigation to give it "a free hand."

Meanwhile, the U.S. Embassy here confirmed today that American authorities have been asked by the Philippine government to assist in tracing the pistol used and in identifying the alleged assassin's fingerprints. The weapon was an American-made Smith & Wesson .357 magnum. In Washington, a U.S. official said the Philippines was told that the last trace of the numbered gun was in a shipment sent to a Thai dealer in 1970.

Police have said only that the killer was a man of about 35, of stocky build and with the nickname "Rolly" stitched into his undershorts. The police have published his picture in Manila newspapers and asked public help in identifying him.

Aquino's wife and five children arrived here tonight from the United States. They were taken to the Aquino family home in suburban Quezon City, where thousands of people have filed past Aquino's body in the past three days.

Prime Minister Cesar Virata and three other Cabinet ministers were turned away from the Aquino home, The Associated Press reported. The four were the first mourners from Marcos' circle of power, AP said. Rep. Stephen J. Solarz (D-N.Y.) was the sole official American among the visitors to the bier.

Aquino's body was moved to a church Thursday morning in a procession followed by a crowd that police estimated at 100,000, The Associated Press reported. Many of the mourners chanted, "Fight! Fight!" as they Marcos Appoints 5 Judges To Probe Death of Aquino By William Chapman Washington Post Foreign Service

MANILA, Aug. 24--Philippine President Ferdinand Marcos appointed a fact-finding commission composed of five judges today to investigate the slaying Sunday of his longtime political rival, Benigno Aquino Jr.

The membership is not likely to satisfy members of the Aquino family and opposition politicians, who have said they hoped for selection of nongovernmental figures and experts approved by the family.

A statement from Malacanang Palace, the presidential residence, said the commission would make "a free, unlimited and exhaustive investigation into all aspects of the tragedy" and report its findings directly to the president.

Aquino, 50, was shot to death as he stepped off an airplane at Manila's international airport. The government has said that a lone--and still unidentified--gunman shot him in the back of the head. The slayer was promptly killed by airport security men, the government has said.

A persistent political critic of Marcos, Aquino had spent three years in self-imposed exile in the United States and was returning here in an attempt to continue his opposition.

Almost no evidence surrounding the killing has been made public yet, and the police have said they are still unable to identify the gunman.

Some members of the opposition United Nationalist Democratic Organization have questioned the government's ability to make an impartial investigation of the assassination and have said the choice of investigators should be made with the approval of Aquino's family.

The chairman of the commission appointed today is Chief Justice Enrique Fernando. It includes a former chief justice, Roberto Concepcion, and three current members of the Supreme Court. All generally are regarded here as friendly to the president and are not known as dissenters in cases involving his government's policy.

The statement said Marcos is offering a reward of 500,000 pesos (about $46,000) for any information leading to the arrest of others involved in the shooting.

Marcos said in a television interview Monday night that the killer may have had accomplices, and several observers have said they considered it improbable that a lone man could have gotten close enough to Aquino to shoot him in the head without assistance from others. The scene of the shooting was guarded closely by airport security officers at the time.

Marcos also ordered all members of the airport security force confined to quarters during the commission's investigation to give it "a free hand."

Meanwhile, the U.S. Embassy here confirmed today that American authorities have been asked by the Philippine government to assist in tracing the pistol used and in identifying the alleged assassin's fingerprints. The weapon was an American-made Smith & Wesson .357 magnum. In Washington, a U.S. official said the Philippines was told that the last trace of the numbered gun was in a shipment sent to a Thai dealer in 1970.

Police have said only that the killer was a man of about 35, of stocky build and with the nickname "Rolly" stitched into his undershorts. The police have published his picture in Manila newspapers and asked public help in identifying him.

Aquino's wife and five children arrived here tonight from the United States. They were taken to the Aquino family home in suburban Quezon City, where thousands of people have filed past Aquino's body in the past three days.

Prime Minister Cesar Virata and three other Cabinet ministers were turned away from the Aquino home, The Associated Press reported. The four were the first mourners from Marcos' circle of power, AP said. Rep. Stephen J. Solarz (D-N.Y.) was the sole official American among the visitors to the bier.

Aquino's body was moved to a church Thursday morning in a procession followed by a crowd that police estimated at 100,000, The Associated Press reported. Many of the mourners chanted, "Fight! Fight!" as they marched, AP reported.