During the last two days of testimony last week, the Khmer Rouge tribunal heard from the relatives of detainees whom Tuol Sleng prison chief Kaing Guek Eav, alias Duch, knew personally.

Im Sun Thy and Phung Sunthary, the wife and daughter of the respected law professor Phung Ton, described for the court on Wednesday how his death had affected them. Phung Ton had at one point taught Duch.

Phung Sunthary said she did not believe Duch's past claims that he had no idea what happened to the professor at Tuol Sleng. But Duch stood by his assertion that he did not know at the time that the professor was being held there, adding that he had been upset himself when he learned of Phung Ton's fate. 

On Thursday, after hearing testimony from the brother of a former classmate, Duch said he had made a conscious effort to ignore friends and colleagues who were sent to the torture facility, an act he said was tantamount to betrayal.

"I would like to reiterate that my friends who were arrested and detained at S-21 were numerous, and I had to get away from them. I betrayed friends and colleagues," he said.