To hear tribunal witness Philippe Jullian-Gaufres talking about his old chum, war crimes defendant Khieu Samphan, is to hear the story of a well-intentioned man, whose popularity was exploited by the Khmer Rouge to legitimise the movement.

What might be called the “Mr Clean” defence – in which it is argued that Samphan knew little of Democratic Kampuchea’s brutalities in his role as the president of the state presidium – is nothing new. But yesterday’s session marked the first time a witness in Case 002 testified almost exclusively to the character of Samphan.

Called by the defence, Jullian-Gaufres recalled a friendship that began in the late 1950s in Paris, when both men were students. Enamored with Southeast Asian culture, Jullian-Gaufres first met Samphan after seeking out Khmer lessons in advance of moving to live in Cambodia. Samphan, the head of the Khmer students union in Paris, impressed Jullian-Gaufres as a focused man. “I believe Khieu Samphan, who was single back then, would spend most of his time focusing on the development of his country by being involved in activities of various kinds,” he said.

The bond continued until the late 1960s, when the Frenchman was working for a company in Phnom Penh, and broke off from 1975 through 1979, the years of Khmer Rouge rule. The two didn’t reconnect until decades later, on a 2005 visit to Samphan’s home in Pailin province, and a separate visit in 2006. These reunions took place about a year before Samphan was arrested for his role in a regime that caused the deaths of almost two million people.

Jullian-Gaufres repeatedly mentioned how modestly Samphan lived. While others enjoyed “sumptuous” lifestyles, the spartan Samphan drove a clunker during his years as an official in the 1960s. In Pailin in 2005, he had a house with no running water. The two later visited the Preah Vihear temple, and villagers they encountered on the way “still had a lot of respect for Khieu Samphan”.

At one point, Jullian-Gaufres compared the defendant to the Queen of England, saying his role was unconnected to real power.

Judge Jean-Marc Lavergne disagreed.

“I’m not entirely sure the Queen of England would ever utter what I am about to read,” he said, quoting an article of the Khmer Rouge constitution unveiled by Samphan decrying the decadent culture of the west.

On what Samphan did from 1975 to 1979, Jullian-Gaufres, who married a Cambodian woman and lost many of his in-laws to the Khmer Rouge, said it wasn’t appropriate to ask.

“The newspapers and books had reported many things, things that called for a sense of calmness to prevail.”

Under questioning from the prosecution, Jullian-Gaufres conceded that his view of Samphan as a figurehead was based on his opinion, not hard evidence. He also said their friendly relationship was the reason he served as a character witness.