"Anyone educated was to be rounded up and executed," Jameson said. "This meant all teachers, lawyers, journalists and eventually anyone who wore glasses. Glasses meant they could read and were a threat."

Jameson said almost 2 million people died as a result of the purges out of a population of 8 million. He said the total number of victims still is being debated.

Jameson said he has visited the killing fields, where Cambodians were beaten to death because the price of a bullet was too high. He's also seen the torture center, which is being documented in the trial.

"It's open to the public. It's obvious they're encouraging the public to see what's happening," he said. "It's good because as part of these trials they documented what happened and documented these torture centers and killing fields."

Jameson's fiancee is the daughter of two Cambodians who were married during the rule of the Khmer Rouge.

"My fiancee's parents married in a mass 'wedding' when a cadre leader simply paired off couples by finger pointing and declaring they were now married," he said. "They stayed together and had five kids and that was not uncommon."

He said his fiancee's parents were lucky to survive the brief but brutal rule of the Khmer Rouge. Vietnam invaded Cambodia in late 1978 and deposed the Khmer Rouge Jan. 7, 1979.

"Any Cambodian of a certain age can recite the exact number of horrible days, months and years the KR was in power," Jameson said.

Duch, 66, is being tried by a U.N.-assisted genocide tribunal for crimes against humanity, war crimes, murder and torture.

Jameson said most Cambodians would rather look forward than back toward such a violent past.

"They're looking toward the future," he said. "They weren't that interested in it. The country is mostly young people that weren't alive when it happened."

The Associated Press contributed to this report.