The genocide trial of a prison chief for Cambodia's Khmer Rouge entered its final stage Monday, as closing arguments began in the historic effort to assign responsibility for the deaths of 1.7 million people three decades ago.

The defendant, Kaing Guek Eav, commanded S-21 prison which punished those accused of disloyalty to the xenophobic communist group. He oversaw the torture and execution of about 16,000 men, women and children during its 1975-79 rule.

If the U.N.-assisted tribunal rules him guilty, the former schoolteacher faces a maximum penalty of life in prison, as Cambodia has no death penalty.

One of the lawyers for the victims evoked the specter of the Nazi death camps of World War II in recalling the Khmer Rouge's atrocities.

Pierre-Olivier Sur said the parents and grandparents of people of his generation had repeatedly said that "the death camps were over and would never happen again."

"The death camps and the mass graves have survived," he declared, referring to Khmer Rouge prisons and the infamous "killing fields," where they dumped their victims. He called for the tribunal to not let crimes against humanity go unpunished.

As much as one-sixth of Cambodia's population perished from execution, overwork, disease and malnutrition as a result of the Khmer Rouge's radical policies _ including the mass evacuation of towns and cities, and the ruthless persecution of alleged rivals.

With some of the handful of S-21 survivors and family members of the dead looking on, another of the victims' lawyers charged that Kaing Guek Eav, also known as Duch (pronounced DOIK), pursued his role with zeal and had no empathy for his victims despite his expressions of remorse.

"Look at them, Duch. Look at these men and women who you wanted to smash, and whose parents and loved ones and children you smashed," said lawyer Philippe Canonne.

"You can smash insects and animals but you can't smash human beings, because one day they will come back, one way or another, or their successors to demand a reckoning," he said.

As he watched the proceedings, Duch showed no emotion. He is expected to give his final statement as early as Wednesday, a day after the prosecution begins its summation. He is charged with crimes against humanity, war crimes, murder and torture.

The closing arguments will conclude Friday, while a verdict and sentence are expected early next year. Under an innovative arrangement, the victims _ known as the 'civil parties' _ were represented at the trial, and their lawyers made Monday's presentations.