It was supposed to be an exciting trip home to surprise his parents in the United States, his family said.

But on May 24, before he boarded the plane at Yangon International Airport, in Myanmar's biggest city, Danny Fenster, 37, was stopped by security forces and inexplicably taken into custody.

Four months earlier, Myanmar's military had seized power in a coup and embarked on a bloody crackdown against protesters, journalists, striking workers, activists and others opposed to the new ruling junta.

Fenster, a US citizen from Detroit, Michigan, was working in Yangon as managing editor of independent news outlet Frontier Myanmar, driving the highly regarded news site's coverage of the fallout from the coup, despite the junta targeting media houses and journalists.

It remains unclear why Fenster was detained at the airport and it is unknown whether he has been charged with a crime. He has not had any contact with his parents, lawyers or officials at the US embassy in Yangon, who have tried to visit him, a state department official told CNN Business.

Frontier Myanmar said they understand he is being held in Insein Prison, Myanmar's infamous clock-shaped penitentiary north of Yangon known for holding political prisoners and having a decades-old reputation for mistreatment and brutal conditions.