Twenty years have now passed since the disappearance of lawyer Somchai Neelapaijit and Thai and international human rights advocates are still waiting for justice and the truth to be told.
They renewed their call for justice on Tuesday.
The human rights lawyer vanished on March 12, 2004, while protecting his southern Muslim clients against torture and other rights violations under martial law.
He was seen being abducted by police. No authorities have been held accountable for his enforced disappearance.
Sunai Phasuk, a senior researcher on Thailand in Human Rights Watch, posted a Twitter message on Tuesday saying that all governments since then have failed to shed any light on Somchai's disappearance.
"Successive governments - including the current PM @Thavisin - have failed to resolve this case. No one has been punished," the message said.
@Thavisin is the official X account of Prime Minister Srettha Thavisin.
Amnesty International Thailand on Tuesday said that Somchai's case underlined the failure of authorities to give the people truth and justice.
"Over the past two decades, Thai authorities have utterly failed to provide justice, truth or reparations to Somchai and his family," Amnesty International's Regional Researchers for Thailand Chanatip Tatiyakaroonwong said on the website.
"This case and many others involving enforced disappearances highlight an entrenched culture of impunity in a country that is now trying to join the UN Human Rights Council."
The United Nations High Commissioner for Human Rights has urged authorities to look into the case and find those behind Somchai's disappearance.
"Thai authorities must comply with the country’s international obligations, investigate this crime and hold the perpetrators of Somchai’s enforced disappearance criminally responsible," it said in a statement released on Monday.
Somchai has a wife, Angkhana, and five children.
Ms Angkhana became an active human rights defender after her husband went missing. She posted a Facebook photo on Saturday showing the room, along with personal items, where he had worked before he was forcefully taken away.
The photo was posted with a message saying her husband was made to disappear because his abductors feared him.