Alan Sipress and Ellen Nakashima, Jakarta – Indonesian police are investigating whether soldiers were behind the killing of two Americans and one Indonesian near the Freeport-McMoRan gold and copper mine in the eastern province of Papua, the regional police chief said today.

Investigators also were exploring the possibility that Papuan separatists or local tribesmen carried out the August 31 ambush. But the determination of the police chief, I. Made Pastika, to examine possible army involvement has put him at odds with Indonesia's powerful military.

Armed forces commanders have continued to insist that separatists ambushed a convoy of Toyota Land Cruisers traveling the foggy mountain road to the mine. The military's Papua commander, Maj. Gen. Mahidin Simbolon, today again blamed the attack – the most violent in the area in 40 years – on the Free Papua Movement (OPM), which has been waging an independence campaign marked by low-level, sporadic violence.

But Pastika, in an interview, said that members of the military may have carried out the attack to extort money or other concessions from the Freeport-McMoRan facility, the world's largest gold and copper mine. Furnishing security for multinational companies has proven lucrative for the military, known by its Indonesian initials as TNI, but Pastika said that some of its members are dissatisfied with the current arrangement.

Investigators are also evaluating the possibility that special forces may have hired local Papuan fighters to conduct the ambush, he said. "There are some rumors about the possibility of TNI or other [military] personnel maybe doing the attack. This is also one of the possibilities," Pastika said. "We are police and cannot ignore any of the possibilities."

The differences between the police and the military over the investigation reflects a broader and occasionally violent rivalry that developed after the two forces, once unified, were split after the 1998 ouster of the long-ruling President Suharto. Though the purpose was to create stronger civilian institutions, with the police playing a greater role in internal security, the two organizations compete across the Indonesian archipelago for control over security and the patronage and money-making opportunities that come with it.

This is not the first time police have focused suspicions on the military over atrocities in the remote province at the far eastern end of the archipelago. The police accused the military's special forces of carrying out the November murder of Papuan separatist leader Theys Eluay, and 12 soldiers have been detained in connection with that killing. If soldiers are found to be involved in the August 31 ambush, it could undercut US plans to restore military ties with Indonesia, suspended in 1999 to protest the army's role in orchestrating widespread militia violence in East Timor.

Simbolon, the Papuan military commander, rejected any suggestion of military involvement in the attack, which killed American teachers Edwin L. Burgon of Sunriver, Ore., and Ricky L. Spier of Colorado and their Indonesian colleague Bambung Riwanto,, all Freeport employees. "No way," Simbolon said, when asked whether special forces or other soldiers could have been responsible.

He said it was clear that the military was innocent because soldiers, who were protecting the police as they investigated the crime, were fired on by separatists on September 1, a day after the ambush. In that exchange, one Papuan was killed, police say. Simbolon said a guerrilla group headed by local separatist commander Kelly Kwalik could have been the attacker. But he said another faction, led by Titus Murib, may also have been responsible. Simbolon said a body recovered from the firefight appears to be that of a member of the Moni tribe, which comes from an area where Murib is active.

Simbolon has vowed to crush the Papuan separatist campaign, raising concerns among human rights and community activists eager to see Jakarta reach a compromise with the independence movement. Simbolon, known for his tough tactics, assumed the top army post in Papua after serving as a commander in East Timor.

Pastika, the police chief, said it remained possible that separatists were behind the attack near the Freeport mine. If so, the ambush, carried out with automatic weapons including M-16 assault rifles, would represent a notable escalation for fighters who have traditionally used bows and arrows.

He said police have learned that the Kwalik and Murib factions each have one or two assault rifles. Pastika said another possibility is that the killings were committed by Papuans jealous of the allowances provided by Freeport-McMoRan to tribes living in the immediate vicinity of the mine. The military has complicated the probe, he said. For instance, soldiers have smudged fingerprints and moved bodies and vehicles, he said, adding that this reflected soldiers' ignorance about how to treat a crime scene.

But Simbolon said that police-military coordination during the investigation has been excellent. "We're in full cooperation with the police," Simbolon said. "The Papuan police chief and me, as always, work together."