BANGKOK (AP) — After spending nine years and more than $300 million to prosecute leaders of Cambodia's Khmer Rouge responsible for the deaths of 1.7 million of their countrymen, a U.N.-assisted tribunal has ended up convicting only three people for the communist group's heinous actions.

Was it worth it?

These kinds of proceedings don't run cheap. The longer-running tribunals covering genocide in Rwanda and war crimes in the former Yugoslavia ran up costs of as much as $2 billion — though both tried many more people than were called to account in Cambodia for crimes committed during the 1975-79 regime of the late Khmer Rouge leader Pol Pot.

On Friday, the tribunal convicted Nuon Chea, 92, and Khieu Samphan, 87, the last surviving Khmer Rouge leaders, of genocide, crimes against humanity and war crimes, and sentenced them to life in prison. The only other person who has been convicted is Kaing Guek Eav, known as Duch, who as head of the Khmer Rouge prison system ran the infamous Tuol Sleng torture center in Phnom Penh.

Justice is the primary goal. But international tribunals, trying people accused of crimes on a national scale, also serve to promote human rights and establish a historical record, among other targets.

Even the most bullish observers acknowledge the shortcomings of the Cambodian tribunal, officially called the Extraordinary Chambers in the Courts of Cambodia, or ECCC. The rules hammered out in extensive negotiations between the United Nations and the Cambodian government hobbled its proceedings in ways that were not always foreseeable.

The ECCC was set up as a hybrid court, meaning every international prosecutor and judge was paired with a Cambodian counterpart. However, what was a political atmosphere encouraging cooperation when the U.N. agreement was signed in 2003 deteriorated, as democratic space has shrunk under Cambodia's long-serving, autocratic Prime Minister Hun Sen.

"Hybrid courts require domestic and international partners to share the steering wheel. They tend to function well only when the two drivers want to head in the same general direction," said John Ciorciari, a professor at the University of Michigan and co-author of a book about the tribunal. "When they do, mixed tribunals can help fill gaps in otherwise frail domestic systems. When interests clash, these efforts to share sovereignty are prone to crash."

The main case in point: Hun Sen — himself a former Khmer Rouge commander who defected from the group when it was in power — declaring no more suspects should be prosecuted, saying without justification that such action could cause unrest.

It didn't help that the U.N. agreement's vague wording of who could be targeted for prosecution — senior Khmer Rouge leaders and those most responsible for the atrocities — proved to be more restrictive than open-ended.

"All tribunals of this character have political restraints, and so that is not unique to the ECCC," said David Scheffer, a law professor at Northwestern University and former U.S. ambassador at large for war crimes. Other points he mentioned that delayed the proceedings included the protection of due process rights and the unusual combination of a civil law investigating judicial procedure alongside a common law prosecutorial model.

"One can always surmise about more being done," said Scheffer, who also served as the U.N.'s special expert on assistance to the Khmer Rouge trials. "But that was the negotiated reality of this particular tribunal."

Nevertheless, he gave high marks to the tribunal's performance, saying its main contribution has been both domestic and international justice rendered against some of the major figures in the Pol Pot regime.

"The Cambodian people sought justice and the ECCC delivered a significant measure of it," Scheffer said in an email interview. "The ECCC also established a historical record, albeit not comprehensive, that otherwise never would have been uncovered."

Adama Dieng, the U.N. special adviser on the prevention of genocide, also said Friday's convictions showed that "justice will prevail, and that impunity should never be accepted for genocide and other atrocity crimes."

Political education is an area where the tribunal has succeeded, said Heather Ryan, who has monitored the trials for the Open Society Justice Initiative, an independent international human rights organization.

"The court has made a huge contribution to helping the world and Cambodians better understand what occurred during the Khmer Rouge regime," said Ryan. "It has triggered discussions at all levels of Cambodian society about not only the past, but concepts of impunity, justice and accountability relevant to the current political situation in Cambodia."

Other observers were less impressed.

Theary Seng, a U.S.-trained lawyer, writer and political analyst based in Phnom Penh, Cambodia's capital, who is an outspoken critic of Hun Sen's government, called the tribunal "a complete failure for international justice" because it didn't accomplish any of the established goals of reconciliation, symbolic justice and combating impunity.

Seng, whose parents were killed by the Khmer Rouge, pointed out that the hope that at least some of the Cambodian judges, prosecutors and lawyers that the government placed in the tribunal would somehow become champions of judicial fairness and the rule of law has been the opposite of fulfilled: they have all been deeply implicated in government abuse and perversion of the domestic justice system.

She said her top concern now was for the integrity of the tribunal's documents to be preserved for researchers.

It is likely that the voluminous documentation used by the tribunal will be handed over to the government or institution controlled by the government, she said.

"This means that the printed documents could be selectively destroyed and the electronic version could be subtly altered," she warned. "Future researchers writing the history of Cambodia will not know what's what."

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Associated Press writer Sopheng Cheang in Phnom Penh, Cambodia, contributed to this report.

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