SAO PAULO, BRAZIL — CHILE'S Supreme Court has moved a step closer to putting on trial two participants in the regime of Gen. Augusto Pinochet Ugarte who are accused in the 1976 slaying of Orlando Letelier, Chile's former ambassador to the United States.The move does not mean that other alleged human rights violators will be tried, but it could bring the former Pinochet regime, including the general himself, under intense scrutinity. The Oct. 14 decision by Chile's Supreme Court to try two former internal-security chiefs in civilian courts was hailed by human rights reformers. The alternative would have been to hand them over to military courts known for leniency toward personnel charged with rights abuses during the 1973-1990 dictatorship. Gen. Manuel Contreras and Col. Pedro Espinoza are accused of ordering the Letelier assassination. Letelier was killed in a 1976 car bombing in Washington D.C. along with his American assistant, Ronni Moffit. He had been ambassador to the US under the socialist government of Salvador Allende Gossens, who was killed during the Sept. 11, 1973, coup. Exiled in Washington, the former ambassador was an outspoken critic of the Pinochet regime. The Supreme Court decision is a historic one for Chilean democracy, according to Sergio Bitar, a federal deputy for the centrist Party for Democracy and a former political prisoner. "This case constitutes a turning point as to the legitimacy of the judicial system in the eyes of Chileans," he said in a phone interview. "It restores lost confidence." With most of the 15 Supreme Court justices appointed by General Pinochet to life terms, many of them on the eve of his 1990 departure from office, the judiciary is one of the pillars supporting his remaining political power. The judiciary was criticized for its weak response to human rights abuses during the regime in a March government report. Many rights activists fault President Patricio Aylwin Azocar for not going beyond the report's finding of 2,000 documented cases of abuse, to punish the perpetrat ors. General Contreras and Colonel Espinoza were indicted in US district court in 1978 for the murders of Letelier and Ms. Moffit, but the Chilean government refused extradition. Testimony in the US case, which sent a Chilean, two Cuban-Americans, and American Michael Townley to jail, offered evidence that the murderers had received orders from Pinochet's security apparatus DINA, the now-defunct National Directorate of Intelligence. Chile's decision to prosecute in the Letelier case was long in coming but was no surprise for many Chileans. Because of the negative impact the accusations had on the country's foreign relations, the military government specifically excluded the case from a 1978 law granting amnesty for human rights violations. For Chileans, the key question is whether the case will touch Pinochet himself. Though the general denies knowing of DINA's day-to-day activities, many believe he gave the order to kill Letelier. Pinochet's role is an especially touchy subject, since he still retains so much power, both as commander-in-chief of the military and through congressmen, judges, and officials he appointed before leaving office. "The case is extremely murky, full of hidden powers" says Mr. Bitar. "We hope to bring down the hidden forces." The case will play out against a backdrop of growing pressure on the human rights issue. Excavations in September in Santiago's General Cemetery unearthed the remains of roughly 60 political prisoners. And during the week of Nov. 3, Chilean human rights groups will host a congress of Latin American associations of relatives of the "disappeared." Activists say that about 90,000 "disappeared" in the region between 1970-1980. Meanwhile, many Chileans are skeptical that justice will be done in the Letelier case. "The legal process in Chile is very difficult," says Ricardo Israel, a lawyer and political scientist at the University of Chile. "It's hard to prove [Contreras] gave the order because many elements which are proof in US courts aren't in Chile."