By Jane Perlez
VIENTIANE, Laos — On the 100th day since the disappearance of a prominent American-educated Laotian agriculture specialist, Secretary of State John Kerry on Monday urged the government here to make public the results of an investigation into what had happened to him, and to return him to his family.
The statement by Mr. Kerry is the second by the United States since the man, Sombath Somphone, 60, was last seen being stopped in his jeep by the police on a main road of the capital, Vientiane, on Dec. 15. It was issued by the State Department in Washington on Sunday as Mr. Kerry visited Iraq.
The refusal by the Laotian government to acknowledge any responsibility for Mr. Sombath’s whereabouts has increased fears for his safety and drawn unusually strong criticism from the United States, European countries and Singapore. (His wife is a citizen of Singapore.)
A poor country of six million people on the Mekong River, Laos is ruled by a Communist leadership composed of veterans of the Pathet Lao insurgency that defeated an American-backed government in 1975.
The government has become increasingly close to China, a northern neighbor. Beijing has financed major infrastructure projects and contributed to the public security system, including the closed-circuit surveillance cameras that captured Mr. Sombath’s last moments before he disappeared.
Two days after Mr. Sombath failed to arrive home on that Saturday in December, his wife, Ng Shui Mong, accompanied by several friends, went to the municipal police station and viewed the video from the surveillance camera near the police checkpoint where her husband was stopped.
As the video played, Ms. Ng and her friends made copies with their cellphones. Those images have been posted on You Tube and on a Web site, sombath.org, as part of an international campaign to get to the bottom of Mr. Sombath’s disappearance.
The video, at times to hard decipher, shows Mr. Sombath being stopped, getting out of his jeep and walking in the direction of the police checkpoint. A motorcyclist then drives up and stops, and then gets in Mr. Sombath’s jeep and drives away. A few minutes later, a white pickup truck arrives at the scene, two men get out and Mr. Sombath then gets into the truck with them. It drives away.
The United States Embassy in Vientiane offered technical assistance to the Laotian government to enhance the quality of the surveillance video so that the license plates on the motorcycle and the truck could become clear, American officials said. The government declined the offer, the officials said.
Much of the American aid to Laos is devoted to public health services and to clearing unexploded ordnance left over from the bombing campaign the United States conducted in an effort to prevent North Vietnam from using Laos as a supply and troop corridor during the Vietnam War.
Neither the United States nor European countries have threatened to cut off aid to Laos over the Sombath case, but instead have tried to emphasize the damage it could cause to the reputation of the Laotian government, diplomats said.
In many respects, Mr. Sombath has special meaning for the United States. He first visited America as a high school exchange student on the American Field Service program in 1969. When he arrived in Wisconsin to stay with a family for a year, he spoke only basic English he had learned from an American Fulbright scholar in Laos.
Later he studied at the University of Hawaii, earning a master’s degree in agriculture, a field that became the focus of his career as promoter of sustainable farming. He founded the Participatory Development Training Center in Vientiane to teach young Laotians the skills needed for community development projects, and he was embraced in Asia and Africa for his pioneering work.
Mr. Sombath gave the keynote address at the Asia-Europe People’s Forum in October 2012 in Vientiane, a gathering of Laotian community leaders and foreign aid workers. The confiscation of land by government authorities was a major topic at the forum, and some of Mr. Sombath’s supporters believe that he was abducted as a warning to silence government critics on that subject.
Mr. Sombath’s wife, Ms. Ng, a former senior official with Unicef, has helped organize a campaign to encourage the government to tell what it knows about Mr. Sombath. A month after Mr. Sombath’s disappearance, Mr. Kerry’s predecessor as secretary of state, Hillary Rodham Clinton, appealed to the Laotian government to come forward with information.
“The Lao government has done this before,” Ms. Ng, said, referring to other unexplained disappearances of Laotian citizens. “But they have never faced this international interest.”
The United States has also expressed concern about the refusal of the Laotian government to help in the investigation of two missing American citizens and a resident, all of Laotian origin, who disappeared this year.
This month, Laotian officials in Savannakhet, a southern province, prevented a team of American investigators from reaching the site where the three men — Souli Kongmalavong, Bounthie Insixiengmai and Bounma Phannhotha — were last seen in January, officials at the American Embassy said.