PHNOM PENH, Cambodia — With a name like the "Peace Corps," you might expect the group to avoid fraternizing with someone alleged to have carried out some of last century's bloodiest crimes against humanity.

But as it turns out, a Peace Corps volunteer in Cambodia has been living with the family of a former Khmer Rouge figure wanted by a UN-backed tribunal for crimes against humanity, war crimes, torture and homicide.

The bombshell revelations, reported Monday by the Phnom Penh Post, are deeply embarrassing for the volunteer program which aims to “promote world peace.”

Meas Muth served as navy chief under the ultra-Maoist Khmer Rouge regime, responsible for the deaths of an estimated 1.7 million people between 1975-79.

His charge sheet makes for grim reading. Among other heinous crimes, a judge at the Khmer Rouge tribunal has charged Muth with murder, extermination, enslavement, imprisonment and persecution on political and ethnic grounds.

A Cambodian woman looks at portraits of victims of the Khmer Rouge at the Tuol Sleng genocide museum in Phnom Penh.

Muth is also accused of being responsible for killings of Vietnamese and Thai civilians, and other foreigners at sea, including the torture and execution of a group of yachtsmen in 1978. He has ignored summons from the tribunal, located in the the Cambodian capital of Phnom Penh, and police have in turn ignored an arrest warrant from the court, leading to accusations of government interference.

As a result, Muth, who denies the allegations and claims to have found peace through devout Buddhism, remains a free man. But how did Peace Corps volunteer Ben Larracey, a teacher at a local high school in remote north-west Cambodia, end up sharing a home with an accused war criminal?

According to the Phnom Penh Post, it was Muth’s son, Meas Sophors, who was originally chosen to host Larracey in September 2013, thereby earning a $110 monthly pay check from the US government. But a few months later, in January 2014, Larracey moved into Muth’s nearby house for a period of several months, possibly due to renovations on Sophors’ home.

He later returned to live with Sophors, but Muth said the young American often visited.

“I am a man who does not like to talk much, so I just say ‘hello’ and ‘how are you?’ in the Khmer language to him,” Muth told the Post.

It appears the Peace Corps only took action after being contacted for the story. The organization did not respond to questions from GlobalPost asking how long it had known that a volunteer was staying with the family of Muth or if Larracey had informed the Peace Corps once he found out about his host family’s history.

“Peace Corps takes the responsibility to place Volunteers in safe and productive homestays extremely seriously,” a spokesperson said in an email.

“As soon as Peace Corps Headquarters learned of this situation, immediate action was taken and the Volunteer in question was removed from their site. Peace Corps will review its processes, as Volunteer safety and security is the agency’s top priority.”

It's a whopper for the US government. Clearly someone was asleep at the switch.

The revelations are also causing embarrassment in Phnom Penh for the US government, a key donor to the Khmer Rouge tribunal and a frequent critic of rights abuses in Cambodia.

“It’s a whopper for the US Government,” said Sophal Ear, author of "Aid Dependence in Cambodia: How Foreign Assistance Undermines Democracy."

“Extensive vetting process? It’s not as if the son had a different last name from his father. Clearly someone was asleep at the switch.”

Sophal suggested that while someone might have “intentionally wanted to embarrass the US government,” it was unlikely.

“As clever as the Cambodian authorities are, even I have to say the plot would be too twisted for their involvement. I guess even the world’s most powerful country can’t be bothered to put two and two together.”

But John D. Ciorciari, an expert on the Khmer Rouge tribunal at the University of Michigan, noted that although Muth’s name as a tribunal suspect had been leaked well before September 2013, when the placement was made, official charges were only laid in March this year.

“It does seem quite possible that staffers missed the connection,” he said in an email. “The real embarrassment is that Muth continues to live freely while facing credible charges of overseeing extensive atrocities.”

Admittedly, the area where Larracey was placed — Samlot district in the “rice bowl” province of Battambang — is home to many former Khmer Rouge cadres, meaning the Peace Corps would be hard-pressed to find a host family without any connection to the brutal communist regime.

Youk Chhang, executive director of the Documentation Center of Cambodia, which researches Khmer Rouge history, said he was not shocked by what had happened.

“Cambodia is gray — definitely gray and broken,” he told GlobalPost.

“It is a society that made up by genocide survivors. Therefore, it is unpredictable and anyone can get caught by it easily. The most important thing is that we must deal with it and we need to look forward.”

In an interview earlier this year, Muth declared that he had forgiven the United States for “throwing bombs on my head”—a reference to President Richard Nixon’s controversial bombings of North Vietnamese and Khmer Rouge targets in Cambodia the early 1970s.

When asked last week by the Phnom Penh Post why he had allowed a young American into his family, the 76-year-old clarified that not all hatchets had been buried.

“I have not forgiven my enemy, but my enemy does nothing to me [now], so I will not do anything back against them,” he said.