A joint U.S.-Indonesian investigation into the ambush of American school teachers in the jungle of Papua, Indonesia, two years ago, has led to the indictment of a member of a provincial separatist movement, the Justice Department announced yesterday. Two Americans and an Indonesian were killed in the ambush in the remote province of Papua and eight others were seriously wounded. Ten school teachers and a 6-year-old girl were returning from a picnic in the rain forest on August 31, 2002, when their two vehicles were attacked by masked assailants.

The teachers worked at a school for the employees of the PT Freeport Indonesia gold and copper mine and were on mine property, which was heavily patrolled by Indonesian military units at the time of the attack.

Last year, a preliminary Indonesian police investigation found "a strong possibility" that the shooting was carried out by the Indonesian military. State Department officials also said the preponderance of the evidence pointed to the Indonesian military. Congress, in classified hearings, also was given evidence to support that preliminary finding.

Indonesian officials had denied the allegations. Gen. Ryamizard Ryacudu, Indonesia's army chief, laid blame on the separatist movement, the Free Papua Movement, shortly after the attack. The separatist group denied involvement.

The 19-count indictment returned by a federal grand jury in Washington on June 16 and unsealed yesterday, charges the commander of the separatists' military arm with two counts of murder and eight counts of attempted murder, among other charges. Anthonius Wamang, 32, an Indonesian citizen, is identified as the operational commander of the National Freedom Force, the Free Papua Movement's military branch. Two of the charges are punishable by death.

"We are very pleased that eventually the truth has been exposed," said Marty Natalegawa, an Indonesian Foreign Ministry spokesman.

Wamang is not in custody, according to other news reports. The United States will have to obtain his extradition to bring him to trial.

"The U.S. government is committed to tracking down and prosecuting terrorists who prey on innocent Americans in Indonesia and around the world," Attorney General John D. Ashcroft said in a statement released yesterday. The Free Papua Movement is not on the State Department's list of terrorist groups.

FBI director Robert S. Mueller III called the indictment an example of "the importance of international cooperation to combat terrorism. . . . The cooperation extended by the Indonesian government enabled the FBI to work in the remotest areas of Indonesia and identify the party responsible for this terrible crime."

Indonesia did not initially cooperate with the probe. FBI investigators were denied access to military personnel they wanted to question, and agents in Indonesia were followed by members of the local military special forces when they first sought to investigate the crime. U.S. and Indonesian officials later engaged in protracted high-level negotiations over what evidence the FBI could to bring to the United States for forensic analysis.

Patsy Spier, the widow of Ricky Lynn Spier, one of the two Americans killed, mounted a campaign to convince the U.S. government to keep the pressure on Indonesia. Spier secured private meetings and pledges from Mueller, Deputy Secretary of State Richard L. Armitage and Deputy Defense Secretary Paul D. Wolfowitz to push the issue with the Indonesian government.

Correspondent Ellen Nakashima in Jakarta contributed to this report.