An undated photo of Siam Theerawut provided by his family.

BANGKOK — The family of one of three monarchy critics who disappeared while exiled in Vietnam said on Tuesday that they hope the trio is still alive, urging the authorities to respect their legal rights.

Kanya Theerawut said she hopes her 34-year-old son, Siam Theerawut, will have a chance to contest his charges in court instead of being disappeared. The activist has been missing since January, his family said.

Siam and two other anti-monarchy activists, Chucheep Chivasut and Kritsana Thapthai, are believed to have been extradited to Thailand from Vietnam on May 8 after they attempted to enter the country with counterfeit Indonesian passports.

Read: Family of Disappeared Monarchy Critic Seeks Answers

“Our country has laws. They should be handled in accordance with the law and not sentenced by others [who are not judges],” Kanya said in an interview, shortly after she petitioned the United Nations for help in locating her son. “Isn’t this what Thai law is all about?”

She added, “I am worried about him.”

However, the Thai authorities have denied having any knowledge about the three’s whereabouts.

Siam’s parents and daughter said they visited the National Human Rights Commission and the Vietnamese Embassy on Monday to look for answers. They also inquired about Siam’s whereabouts at the police’s Crime Suppression Division on May 9, but went home empty-handed.

Nonetheless, Kanya said she has a slice of hope because a policeman told her that the military may be holding the trio incommunicado if they really were transported to Bangkok on May 8, as has been the case with some activists in the past.

Siam and his two companions are vocal members of the Organization for Thai Federation, which calls for a republic to be installed in Thailand. The trio has produced numerous Youtube videos criticising the monarchy.

For their activism, the three are wanted in Thailand for insulting the monarchy and failing to report when summoned by the junta after the May 2014 coup.

Siam fled to Laos the same year as the coup. His younger sister Ink Theerawut said in an interview that she lost contact with Siam in January, but thought at the time he was safe.

Her confidence sank when a friend of Siam contacted her last week with photos of what appeared to be counterfeit Indonesian passports and claimed that they were deported from Vietnam.

She still has hope that the Thai authorities have him in custody, but is also fearful that he may be tortured and eventually killed.

“I just want to know if he is safe and where he is,” said Ink, herself a civil servant. “If he is brought to the court, at least we can visit him.”

But a friend of Siam who is also living in exile to avoid lese majeste charges fears for the worst. Anti-junta campaigner Nithiwat Wannasiri said on Tuesday that it never turns out well when someone in the exiled community goes missing for a week.

“Anyone out of contact for this long is most likely no longer alive,” said Nithiwat, who said he has been living in one of Thailand’s neighboring countries for the past five years.

He pointed to five similar cases, including three anti-monarchists who went missing in Laos late last year. Mutilated bodies of two of them were later found on the Thai side of the Mekong River, while the third was never accounted for.

Nithiwat said the latest disappearance has reminded him that it is not safe to stay in the country where he has sought shelter, which he declined to identify. The activist said he’s been trying to relocate to another country far from Thailand.

Additional reporting Teeranai Charuvastra