Two years ago this week, in the Laotian capital of Vientiane, a retired UNICEF official named Shui Meng Ng and her husband drove home for dinner. As they caravaned through the crowded city center—she in the couple's beige hatchback, he in his battered Jeep—Ng lost sight of the Jeep in her rearview mirror. She has not seen or heard from her husband since.

Ng's husband, Sombath Somphone, is well known in Laos for his decades of work on behalf of farmers and sustainable farming practices. A small man with close-cropped white hair and a broad, even-toothed smile, he has a gentle poise that belies a strategic mind. At times, his patient reform efforts have even enjoyed support from the notoriously secretive and repressive Laotian government.

But not long before he disappeared, he challenged the massive land deals the government has negotiated in recent years. Those sales and leases, many of them to Thai, Vietnamese, and Chinese investors for logging, mining, and large-scale agriculture, have left thousands of rural Laotians with no land and little compensation. They've even sparked popular protests—a rare occurrence in Laos, where political speech is tightly controlled.

Somphone spoke out publicly against the deals.

International NGOs and foreign ambassadors have been calling for answers since soon after he disappeared. On December 15, the second anniversary of his disappearance, 82 NGOs issued a statement condemning "the Lao government's ongoing refusal to provide any information regarding Sombath's fate or whereabouts."

"For the international community, the focus is on not forgetting—on not letting this slip away," says Phil Robertson, deputy Asia director for Human Rights Watch. For Robertson, there is "no doubt whatsoever" that Laotian government officials were involved in Somphone's disappearance.

Two days after he vanished, members of his family went to the local police station. Some young officers there agreed to show them security camera footage of the area where Ng last saw her husband's Jeep.

The footage shows that the Jeep was stopped by police officers. Somphone, still wearing shorts and a T-shirt from his regular Saturday afternoon Ping-Pong game, got out of the vehicle and stood at the side of the road. Moments later, a lone motorcyclist arrived, parked his bike, and drove away in the Jeep. Immediately afterward, an unmarked white pickup pulled up.

Somphone, accompanied by one or two other people, got into the pickup and was driven away.

After Somphone's relatives watched the footage at the police station, the officers allowed them to film it on cell phones and cameras. Somphone's supporters soon posted the video online. So far, however, the Laotian government's public responses to international demands for a serious investigation have consisted of little more than a cursory investigation and expressions of bemused dismay. (Neither the Laotian Ministry of Foreign Affairs nor the country's United Nations mission responded to requests for comment for this story.)

For much of the past two years, Ng has traveled the world, pressing for answers. This past October, she addressed the Asia-Europe People's Forum in Milan. "To this day I am still in shock and in grief," she said.

Laotian authorities say they have no idea where Somphone is or who abducted him. When Somphone's relatives went to the police station and asked about the young officers who showed them the security camera footage, they were told that the officers were no longer there.

A Deceptive Facade

To foreign visitors, Laos can be cinematically seductive. Morning mist rolls over mountains and teak plantations; young monks in saffron robes stroll past crumbling Buddhist stupas and fragrant French bakeries; farmers goad sulky water buffalo.

Parts of the country still look much as they did in 1952, when Sombath Somphone was born in a small village south of the capital.

At age 16, at a French lycée in southern Laos, Somphone was recruited by the American Field Service exchange-student program and left for a year of study in Wisconsin. It was 1969. His country was in a civil war; the North Vietnamese Army had invaded Laos in support of the Pathet Lao, the communist insurgency, and the United States Air Force was dropping hundreds of millions of cluster bombs on the Plain of Jars, in the strategic northeastern corner of Laos. Meanwhile, Somphone was living with a Wisconsin host family, joined the high-school wrestling team, and learned to drive a snowmobile. For the first time, he recalled later, he was beginning each day sure of having enough to eat.

Along the way, Somphone decided that his mission was to improve farming back home. He went to the the University of Hawaii on a USAID scholarship. When he graduated in 1975, the Pathet Lao had just defeated the U.S.-supported royalist forces, and the country was in chaos.

Reluctantly, he stayed on in Honolulu and began to pursue a Ph.D. in agronomy. That's when he met Ng, who was earning her Ph.D. in sociology. She was from Singapore, and like Somphone, she was the eldest child in a poor family.

When Ng was asked to join the faculty of the Institute of Southeast Asian Studies in Singapore, she introduced her new husband to the institute's horticultural researchers, hoping that he would also find work in Singapore. "He just laughed and said, 'You guys grow flowers,'" Ng remembers. "He told them, 'In my country, we need food.' "

Biofertilizer and Buddhism

In 1975, when Somphone was finally able to return to Laos for a visit, he found that government officials were suspicious of an American-educated prodigal son and had little interest in supporting him. He persisted, however, and during longer and longer stays in the country, he embarked on work that was practical and scrupulously apolitical.

He knew that Laotian farmers needed fertilizer and that most couldn't afford the commercial ones. With a small grant from the American Friends Service Committee (AFSC), he researched Azolla, a fast-growing water fern, and began to promote its use as a biofertilizer. He encouraged farmers to grow rice for market but also to improve their own diets by growing vegetables and raising fish and fowl.

Carol Doolittle, the co-director of the AFSC in Laos at the time, remembers Somphone as deceptively diffident. "You'd sit and talk to him, and he'd listen with his eyelids about a third of the way closed—you'd wonder, 'Is this guy about to fall asleep?'" Doolittle soon realized that Somphone was energetic and organized, and passionate not only about better fertilizers but about a better society.

Years of war had destroyed the country's educational system, and most educated Laotians had fled or been killed. So in 1996, Somphone founded an independent educational organization called the Participatory Development Training Center (its acronym, PADETC, sounds to Laotian speakers like padaek, the distinctively Laotian variety of fish sauce).

With PADETC, Somphone expanded his agenda. The organization promoted fuel-efficient stoves for rural women. It established a recycling center in Vientiane that is now the country's largest, processing and exporting more than 2,000 tons of recycled paper and plastic to China and Vietnam in 2013. It organized a countrywide network of 300 artisans and helped market their crafts. PADETC was the first and only organization of its kind in Laos, and many hoped it was a sign of increasing freedom in the country.

In the mid-1990s, Somphone became intensely interested in "engaged Buddhism," a philosophy that Westerners associate with the teachings of the Dalai Lama and Thich Nhat Hanh. He taught his PADETC students to use Buddhist principles to address controversial social issues such as human trafficking and AIDS, and to speak about these and other issues in public.

Somphone is idealistic but not naive, his colleagues say, and he knew that even the mildest criticism of government policies was dangerous. Over the years, several friends with ambitions to better Laos had disappeared, while others had been imprisoned. These abuses are largely hidden from international view: After a visit to laid-back Laos, outsiders often conclude that the country is ruled not with an iron fist but with quaint incompetence and beery charm.

"Laos has been extraordinarily good at hiding its dirty laundry," says one longtime aid worker. "By comparison, Myanmar and North Korea are hanging everything out for the world to see."

View Images In September 2005 Somphone vacationed in Bali with his wife, Shui Meng Ng. Since his disappearance, she has traveled the world seeking support for his cause. Photograph by Sombath Somphone Family, AP

Speaking Out Against Land Grabs

In the late 1990s, after years of political and economic isolation, Laotian government officials had begun to court international investment. They agreed to Thai-financed hydropower dams along the Mekong River and to a proposed high-speed railway connecting Vientiane with the Chinese provincial capital of Kunming.

And they fast-tracked sales and leases of land. A 2012 inventory by Switzerland, Germany, and the Laotian government itself estimated that land deals with both domestic and foreign investors covered almost three million acres of Laotian land-five percent of the country.

When Laos was chosen as the host of the 2012 Asia-Europe Meeting, Somphone was asked to organize the Asia-Europe People's Forum, a parallel gathering of grassroots activists. In an address to the forum in mid-October, Somphone mentioned the land issue. "Economic development and promotion of investment should not undermine people's land ownership," he said. It was a bland statement, but a daring move: It was almost certainly the first time a Laotian had used an official setting to criticize the land sales.

Somphone had worked closely with Laotian government officials while organizing the conference, and he believed they were prepared to tolerate this and other expressions of dissent. But his optimism was apparently misplaced.

Several attendees said they were intimidated and threatened by government officials at the forum, and one Laotian attendee reported that she was harassed even when she returned home. After the conference, Anne-Sophie Gindroz, the Laos country director for the Swiss NGO Helvetas and an ally of Somphone's, wrote a letter to several aid agencies. "We are working in a challenging environment," she stated. "This is a country governed by a single-party regime, where there is little space for meaningful democratic debate, and when taking advantage of that limited space, repercussions follow."

On December 7, a Friday, Gindroz was called to a meeting at the Ministry of Foreign Affairs and told that she had 48 hours to leave the country. In an official notice, the ministry cited her letter and criticized her "unconstructive attitude" toward Laos.

On December 15, the following Saturday, Somphone disappeared.

"At first, I thought, 'They have to let him go. This is on camera,' " Ng says. But as days turned into weeks, Somphone's supporters began to fear that whoever was responsible for his disappearance was simply waiting him to be forgotten.

Whether this all-too-familiar strategy will succeed with someone of Somphone's stature remains to be seen. Several NGOs are now preparing to oppose Laos's planned application for a seat on the U.N. Human Rights Council, citing both Somphone's case and the continued eviction of Laotians from land sold to foreign interests. "We can't let the Lao government win just because people get tired," says Robertson, of Human Rights Watch.

"Laos was a repressive society before Sombath was disappeared, and it's a repressive society now," emphasizes Ian Baird, a professor of geography at the University of Wisconsin-Madison who lived in Laos for many years. "But this is the first time that somebody close to a lot of foreigners, somebody with an international reputation, has been disappeared."

View Images An ad in a Vientiane newspaper seeks information on Somphone. The Laotian authorities say they have none. Photograph by Gilles Sabrie, LightRocket/Getty

Bringing Her Cause to the U.S.

This past spring, Ng traveled to the U.S. to bring attention to her husband's case. At Portland State University in Oregon, she gave a slide presentation about him. Ng is a tiny woman, with chin-length graying hair and a determined air. Dressed in a dark blazer and trousers, she spoke calmly and clearly-a former university professor giving a well-rehearsed lecture.

At the end of her talk, she fielded several questions from the audience, including a few from Laotian-American dissidents who wanted to make Somphone's case a rallying point for their longstanding opposition to the regime. Ng, who treads a fine line between calling out the Lao government and antagonizing it, resisted such suggestions.

"I know what he would want, and he wouldn't want that," she said. "Sombath has no intention or desire to take on any political agenda. All he wanted to do was to serve the poor, the young, the next generation."

An elderly white woman raised her hand and asked if Ng felt safe returning to Vientiane. When Ng started to answer, her questioner gestured for her to speak up. Ng raised her voice, and it suddenly filled with emotion.

"What are they going to do?" she said raggedly. "Kill me? Disappear me? Kick me out of the country? They've already taken my husband. I'm not going to succumb to fear."