"Can you describe to the Chamber the events from the day of your arrest until you were transferred to S-21 prison? Can you describe all the events within that period?" "Mr. President, I will describe, based on my recollection of the events, from my arrest."

Stories of brutality and terror have filled the courtroom for the past two and a half weeks  as victims from the S-21 prison testimony testified against Khmer Rouge prison defendant Kaing Guek Eav, better known as Duch. 

"My force would guard those prisoners and the executioners would get ready at the pit. Guards would post at the gates and each prisoner would be walked to the pit to be killed," 54-year old Him Huy said.

"When they were killed, first they were asked to sit at the edge of the pit, then they would be struck, then their throats would be slashed, then guards would take off their clothes and their handcuffs," he added.

In March Reuters reported that Duch said in a speech to the Cambodia tribunal he felt "heartfelt sorrow" and accepted responsibility for torturing and executing thousands of inmates.

"I am responsible for the crimes committed at S-21, especially the torture and execution. My current plea is that I would like you to please leave an open window for me to seek forgiveness," he said. "This is only the remedy that can help me to relieve all the sorrow and crimes I have committed."

Norng Chan Phal, the son of one of the killed prisoners, said that Duch 'has blood on his hands'.  "When we arrived at Tuol Sleng the Khmer Rouge soldiers pushed my mother from the vehicle," he said. "I didn't know what she had done wrong, I didn't understand why they were punching and kicking her and treating her so badly.

He tried to find her later that week: "I kept running and crying for my mother, searching for my mother. Like almost everyone else who was imprisoned there, she had been killed. I never saw her again."

Duch disputed some of the witnesses’ testimony. He said, according to his records, Phal had already been killed. He also questioned the testimony of a man who said he had survived the jail when he was an 8-year old boy. Duch said confidently that he had made sure all children who entered the prison with their parents were killed.

"The more I met the prisoners, the more I was affected. I therefore avoided seeing them. I did not want to see the reality that did reconcile with my feelings. I did not allow myself to see or hear", he said.

About 1.7 million people died during the four years the Khmer Rouge was in power. That is almost a quarter of Cambodia's population.

Duch is first leader of the communist regime to stand trial at the Extraordinary Chambers in the Courts of Cambodia (ECCC). He is one of five Khmer Rouge leaders who have been detained by the court for their alleged roles in Cambodia's Killing Fields.

He was indicted last year for overseeing the torture and extermination of more than 12,380 men, women and children when he headed Phnom Penh's Tuol Sleng prison, known as S-21.

All suspects before the genocide court held high level military positions in the Khmer Rouge regime. The regime implemented radical policies that lead to the deaths of an estimated 1.7 million people from starvation, disease, overwork and execution. Khmer Rouge leader, Pol Pot, never faced justice and died in his jungle hideout in 1998.

Read the transcripts of the trial here.

Watch the beginning of the testimonies below: