The former number two leader of Cambodia's brutal Khmer Rouge regime says he and his comrades were not “bad people.”

Nuon Chea told Cambodia's U.N.-backed war crimes tribunal Monday that he did not want the “next generation” to “misunderstand history” and believe the Khmer Rouge were “criminal.”

Reputed Khmer Rouge chief ideologue Nuon Chea, former head of state Khieu Samphan, and former Foreign Minister Ieng Sary are on trial in connection with the Khmer Rouge's rule from 1975 to 1979, during which up to a quarter of Cambodia's population was killed.

Nuon Chea blamed Vietnam for the killings in his court testimony.

The trio of defendants are all in their 80s.

Prosecutors are expected to seek the maximum penalty of life in prison for the defendants, though many fear they will not live long enough to be brought to justice.

The trial is expected to last two years.

A fourth defendant — Ieng Thirith — has been ruled unfit to stand trial because she has dementia.

The Khmer Rouge's supreme leader Pol Pot died in 1998 in a jungle camp, where he was held prisoner after his former comrades turned on him.