BANGKOK >> A year ago, Ng Shui-Meng watched a closed-circuit police video in disbelief as it revealed the moment her husband, the most prominent civil rights advocate in Laos, disappeared.

It shows Sombath Somphone, a University of Hawaii and the East-West Center alumnus, being stopped by traffic police on his way home around 6 p.m. on Dec. 15, 2012. A man in a black windbreaker emerges from the police post and drives his car away. Two other men then escort the 61-year-old activist into a pickup truck.

His wife, who obtained the video a day after his disappearance, still doesn’t know what happened next.

The apparent abduction has sent a chilling message to the country’s already fragile civil society, and exposed Laos as one of Asia’s most repressive societies rather than the languid land of smiles of backpacker blogs and tourism boosters.

Laos’ media are under total state control, security watchdogs operate down to the grassroots and foreign human-rights organizations are banned. The communist government responds to even the small and peaceful public protests which periodically surface with swift suppression and arrests.

The landlocked Southeast Asian country of 6.5 million is not known to have gulags or a large number of political prisoners. Dissidents and rights activists say quiet but sharp injections of fear impose silence and self-censorship on a largely apolitical population.

“Every repressive regime has its own way of dealing with dissidents. In Laos, they disappear people without a trace,” said Phil Robertson, the Bangkok-based deputy director of Human Rights Watch Asia.

Laos, one of five single-party communist governments left in the world, has maintained a wall of silence around what it says is an ongoing investigation into Sombath’s disappearance, despite appeals from Western governments.

It is among the world’s poorest nations and is heavily dependent on billions of dollars in international aid, but donors have shied away from using that aid to press for democratic reform. Foreign aid groups working in Laos have been largely silent: A network of 70 of them did not even mention Sombath at a high-level meeting with the government last month.

Responding to pleas from world leaders and Shui-Meng, Sombath’s Singapore-born wife of 30 years, the government has said only that his kidnapping may have been motivated by a personal or business conflict.

“I’m still hoping he is alive and will come home. I will stay in Laos to continue working to find him. I still want to know the truth,” Shui-Meng said in an interview.

Sombath is from a poor farming family but was educated in the U.S., at the University of Hawaii. He founded the Participatory Development Training Center in 1996; its projects range from organic farms to model rural schools to enlisting monks in helping fight drug abuse among youth. In 2005, he won the Magsaysay Award, Asia’s equivalent of the Nobel Peace Prize.

Sombath never advocated overthrowing the government and did not point fingers at individual powerbrokers. Shui-meng said her husband enjoyed support from a number of government officials, and some initially helped her as she tried to discover what had happened to him.

“Sombath has no political ax to grind. He is not anti-anything,” she said. “The only thing he wanted was for Lao youth to actively contribute toward moving the country forward. Certainly that cannot be an offense. Or can it?”

Sombath might have angered the government in October 2012 at the Asia-Europe People’s Forum in Vientiane, the Laotian capital, when he criticized focusing on economic growth while ignoring its negative impacts.

“We need to give more space to the ordinary people, especially young people, and allow them to be the drivers of change and transformation,” he said. “Hearing from the voices of the people is the first step to transforming the power structure.”

Such words came amid stirrings of unrest in the countryside over issues that Sombath had touched on: land grabs to make way for Vietnamese and Chinese plantations, forced relocations of villagers from dam sites, the illegal destruction of forests by powerful figures. And social media was booming: Facebook users doubled in one year, to some 400,000 at present, according to the government-run Vientiane Times, and a few users criticized the government in words and cartoons.

Grant Evans, an Australian scholar and author of several books on Laos, said he believes the government moved against Sombath to send “a very clear message to those who did not understand where the limits lay.”

A Lao dissident who requested anonymity out of safety for his family said getting rid of Sombath eliminated a “model of one who dared to resist the government. … There are others, but none so brave.”

The government has taken overt steps to quiet dissent in other cases.

A call-in radio program popular with those complaining about land grabs and corruption was ordered off the air in January 2012 and the presenter, Ounkeo Souksavanh, has since left the country. The government banned the Australian film “The Rocket,” about a poor family forced from their home into a shantytown to make way for a dam.

A week before Sombath’s disappearance, officials gave Anne-Sophie Gindroz, head of the Swiss nonprofit group Helvetas, 48 hours to leave Laos after she wrote a letter to donors saying the one-party system stifled debate and created a hostile environment for aid groups. Most recently, the Vientiane Times said social media will be regulated so they can be utilized “in a constructive manner.”

“Everyone is very scared,” Robertson said. “They say, ‘If it can happen to Sombath, it can happen to me.’

“The government is so absolutely opaque that you just don’t even know where you can cross the line.”

The government denies holding any political prisoners or kidnapping dissidents, except for three people who remain jailed for their roles in a quashed student protest in 1999. But Amnesty International has identified several other protesters who have been imprisoned.

Two members of the Hmong ethnic minority have been held since 2003 for escorting foreign journalists to report on atrocities.

Some of the country’s 250,000 Christians have been arrested for proselytizing. Others have disappeared or been evicted without compensation, according to Mervyn Thomas, who heads the England-based Christian Solidarity Worldwide.

Sompawn Khantisouk, the owner of an ecotourism lodge who had spoken out against the forced resettlement of villagers, vanished in 2007. Authorities told his wife the same thing they told Shui-meng: that her husband might have been kidnapped because of a business or personal conflict.

Some believe Sombath is alive in a remote camp prison. Others note that he was ill at the time of the kidnapping and surmise that he died under interrogation. Some say he was simply executed.

Calls and emails seeking comment from officials in Vientiane and the Lao Embassy in Washington were not answered.

The European Union, one of the leading donors to Laos, has stated that the government’s statements about Sombath’s case are “neither sufficient nor convincing.”

“In our view, it seems impossible that the government knows nothing about the case. We did not get convincing answers to any of our questions,” said Werner Langen, an EU parliamentarian, during a visit to Laos in October.

Washington has also sought answers. Its embassy in Vientiane put up a banner reading “Where is Our Friend Sombath?” on its water tower, but only for a day.

Some activists believe Laos will do nothing until the international community takes tougher measures.

Vanida Thephsouvanh, who heads the Paris-based Lao Movement for Human Rights, said Lao leaders have managed to “harvest financial assistance from the international community for many decades. Why should they change their methods when no single concrete action has been taken by the international community to press them?”

Foreign aid agencies in Laos variously ascribe their publicly docile stance to a “keeping silent to protect local partners” strategy and believing that it is better to do good work quietly than protest and risk expulsion.

Experts say there are reformists in the government but hardliners remain in control, taking advantage of the poverty, low education level and general laid-back attitude of the population. Civil society, largely Vientiane-based, is small.

“Lao citizens, behind their smiles, have become expert in the rules of silence and self-censorship,” Vanida said. “They do what they can to live, not to create conflict with the established order. It is a country where fear prevails, and the fear is much stronger and more palpable after Sombath’s disappearance.”