ULAANBAATAR (Reuters) - A closed court in Mongolia has convicted three men of the 1998 murder of Sanjaasuren Zorig, a politician remembered for leading the East Asian country’s peaceful transition to democracy.

Nicknamed the “Golden Swallow of Democracy”, Zorig was credited with saving lives during anti-government protests in Mongolia in 1990. His murder has been likened to the assassination of U.S. President John F. Kennedy and sparked a manhunt that involved authorities in Britain and Germany.

Zorig was Mongolia’s minister of infrastructure and was widely expected to become prime minister of the fledgling democracy in 1998 when he was assassinated in his home at the age of 36.

Mongolian media identified the three suspects as B. Sodnomdarjaa, Ts. Amgalanbaatar and T. Chimgee, and said they had been found guilty of murder by a panel of judges on Tuesday after a hearing held behind closed doors since October. They were each given prison sentences of between 24 and 25 years.

Reuters was unable to reach the courts responsible for the verdict. The Ministry of Justice also did not respond to requests for comment.

It was not known how the three men had answered the charges, how they were represented in the court, or when they were arrested.

Mongolian deputy prime minister Tsend Nyamdorj questioned the decision to hold the trial behind closed doors.

“This is very a dangerous practice, in which a court reaches a verdict of murder in secret,” he told parliament on Tuesday. “To me, it looks as if you are trying to hide the fact that you are being repressive.”

Zorig’s sister, Oyun, who heads the pro-democratic Zorig Foundation and is a former government minister, said in a statement sent to Reuters she and her family did not think justice had been done.

“We also requested that the case is de-classified and the court is open,” she said. “Unfortunately, the request was not accepted.”

Dale Choi, an analyst with Mongolian Metals and Mining, likened Zorig’s murder to Kennedy’s 1963 assassination.

“There are a lot of unanswered questions,” he said on Tuesday. “I think today’s court ruling did not answer all these questions.”

Police detained several people for questioning during the investigation, including Zorig’s widow, Bulgan, who is alleged to have witnessed the murder.

Zorig’s murder, though not widely known outside Mongolia, was central to the arrest of intelligence official Bat Khurts in London in 2010 after a warrant was issued by German authorities.

Khurts was detained for his involvement in the 2003 abduction and forced repatriation of Mongolian dissident Enkhbat Damiran, said by Mongolian authorities to be a suspect in Zorig’s murder. Enkhbat eventually died in police custody.

Khurts was released by Germany in 2011 shortly before a visit to Mongolia by Chancellor Angela Merkel, and is now the head of Mongolia’s General Intelligence Agency.