The U.N.-backed Cambodian tribunal trying Khmer Rouge leaders for atrocities committed while they ruled the country acknowledged Monday that only a handful of former high-ranking officials will face justice for their crimes.

The tribunal explained in a statement the dismissal in February of a case against Im Chaem, a middle-ranking Khmer Rouge district chief whom prosecutors had charged with crimes against humanity, including murder, extermination and enslavement.

The statement said the court's co-investigating judges concluded that Im Chaem was not high-ranking enough to fall into the category of senior leaders, and she also did not qualify for prosecution as a person "most responsible" for atrocities, because the evidence of specific crimes attributed to her did not meet acceptable legal standards.

It pointed out, however, that dismissal of the case against Im Chaem, who is in her seventies, "does not equate to a statement that no crimes were committed by a charged person."

á¢ááááááá¸á¢áá¹á á áá á FILE - Im Chaem spoke to VOA from her home in Anlong Veng district in Udder Meanchey province, April 20, 2017. (Sok Khemara/VOA Khmer) FILE - Im Chaem spoke to VOA from her home in Anlong Veng district in Udder Meanchey province, April 20, 2017. (Sok Khemara/VOA Khmer)

As a district chief in the northwestern province of Banteay Meanchey, Im Chaem allegedly ran a forced labor camp to construct an irrigation project and was accused of responsibility for the deaths of possibly thousands of laborers.

The tribunal's statement also said that under the agreement that was negotiated to establish the tribunal, no other Cambodian courts have jurisdiction over human rights violations committed by members of the communist Khmer Rouge, whose harsh 1975-79 rule is generally considered responsible for the deaths of 1.7 million people from execution, overwork and neglect of medical care.

The absence of an alternative court to try such cases means "only a certain small group of people will ever be prosecuted in the courts of Cambodia for the atrocities" during Khmer Rouge rule, it said.

"It is undoubtedly difficult for the public and the victims to accept that even the soldiers who routinely killed small children by bashing their heads against trees or who had competitions about who could kill the greatest number of people, should not face justice," the statement said.

"In many domestic criminal justice systems, such conduct would attract a whole life sentence without parole and in some countries possibly even the death penalty for each individual act of each individual offender."

The agreement to limit such cases to the U.N.-assisted tribunal "was a conscious political choice during the negotiations, balancing the call for integration of the remaining Khmer Rouge into society against the desire for some form of judicial closure for the horrendous suffering of the victims," the statement said.

The tribunal has already convicted two high-ranking Khmer Rouge leaders, Khieu Samphan, the 85-year-old Khmer Rouge head of state, and Nuon Chea, the 90-year-old right-hand man to the group's late top leader, Pol Pot. A second trial of the two on separate charges was recently concluded and is awaiting a verdict.

Also convicted earlier was the head of its prison system, who ran a torture center in Phnom Penh. Cases against a handful of other suspects are in the judicial pipeline.

The head of the Documentation Center of Cambodia, which has collected massive amounts of detailed evidence about the Khmer Rouge, said he was disappointed with the statement's explanation.

Its redaction of the evidence against Im Chaem — based on the rule of presumption of innocence — means that the public at large is unable to judge the correctness of the decision to dismiss the case, Youk Chhang said in an email.

He accused the co-investigating judges of "compromising justice."

The tribunal's statement said the evidence collected by the center dealing with the charges against Im Chaem could not be taken into account because it was gathered in a manner not suitable for legal purposes.