Forty-one years later, their paths converged again, in a way. Obama this week became the first sitting US president to visit Laos. Sombath, meanwhile, has vanished -- stopped on a street in this sleepy Mekong outpost in 2012, stuffed into a pick-up truck, and never heard from again.
Lao authorities have remained silent on the teacher and activist's disappearance, drawing the concern of human rights groups like Amnesty International and Human Rights Watch. Those organizations pressed Obama ahead of his trip here to raise Sombath's case with Lao President Bounnhang Vorachith.
Before he was taken, Sombath was a prominent activist in Laos, though not a strident opponent of the government. Focused mostly on advancing development in the country's rural provinces, he was critical of development plans that forced villagers from their homes.
On Thursday morning, Sombath's wife, Shui Meng Ng, met with Ben Rhodes, Obama's deputy national security adviser, for 20 minutes in the Vientiane hotel where the President is staying. In an interview afterward at her home here, she said Rhodes assured her the President raised the issue of human rights broadly in his meeting, but didn't press her husband's case directly.
"(Obama) is in a position to say a lot of things that not very many Lao people may have the courage nor necessarily the avenue to say," she said. "He has the ears of the highest leaders in Lao party and government."
"He could have said more," she continued. "That's from my own personal perspective. He could have stressed more about human rights, particularly about some of the rights violations, including disappearances."
In his dealings with the Lao government this week, Obama is facing the same delicate challenge he faces with authoritarian governments around the globe: How to raise human rights in a meaningful way while avoiding a confrontation that could sour important diplomatic partnerships.
In China, the first stop of Obama's final Asia swing, the topic barely arose, at least in public. During meetings with Prime Minister Xi Jinping, Obama said he would be "candid" in his approach to human rights, but he avoided mentioning any specific cases during his public remarks.
In Laos, the balance is complicated by a haunted period that saw the US bombard this landlocked Southeast Asian nation with millions of bombs during the Vietnam War. Obama worked to reconcile that past this week by announcing $90 million in new aide for clearing unexploded bombs. But the horrors of millions of American explosives still embedded in fields here muddied his standing in pressing leaders on their own human rights transgressions.
Those transgressions are grave, say rights groups. Eight cases of disappearances in Laos have been referred to a United Nations working group since 1994, but the actual number of incidents could be higher.
"We believe that there are dozens more cases, especially from rural areas, or ethnic minority enclaves, where people have disappeared," said Phil Robertson, the deputy director for Asia at Human Rights Watch. "Laos is very opaque in the way its government and its prison system work, and people can literally be held and the key thrown away."
During remarks in Vientiane on Tuesday, Obama insisted the US would "continue to speak up on behalf of what we consider universal human rights, including the rights of the people of Laos to express yourselves freely and decide your own future."
But as he's argued in places like Saudi Arabia, China and Vietnam, Obama insisted a cooperative relationship was the best path toward progress on human rights.
"Even as our governments deal candidly with our differences, I believe, as we have shown from Cuba to Burma to Vietnam, the best way to deliver progress for all of our peoples is by closer cooperation between our countries," Obama said.
Speaking ahead of his meeting with Sombath's wife, Rhodes said it's standard for the President to raise human rights concerns broadly in his meetings with leaders, but for specific cases to be raised separately, and at a lower level.
"The President addresses these issues around civil society and human rights in his meetings, and then we tend to raise individual cases with the government around those meetings," he said. Sombath's case, he said, has long been on the US radar.
"We stay in regular contact with her and we care very deeply about her case and her husband. We believe that she deserves to know what happened to her husband and what the status of his case is," he said. "The response that we get from the Lao government is what she referenced, which is that they're continuing to investigate this. And oftentimes, they indicate that they do not know and that there is an ongoing investigation."
For Shui Meng Ng, a blackout on her husband's case persists.
"I have no information," she said. "That's the hardest part."