But the government had no compunction about incarcerating Mr. Win Tin, whom Ms. Aung San Suu Kyi and other party leaders called Saya, or “the wise one.” It accused him of being a Communist, a charge he denied.

As described in a memoir, “What’s That? A Human Hell” (2010), his imprisonment, beginning in 1989, was harrowing. He was placed in a tiny cell in what had been a dog kennel and given no bedding. He was fed sparingly and given inadequate medical care. An operation for a strangulated hernia, performed in a dirty prison hospital cell, resulted in the loss of a testicle. He lost most of his teeth in a beating and was then denied dentures. He had two heart attacks in prison. Much of the time he was in solitary confinement. He was deprived of sleep. He was denied visits from the Red Cross. New charges were often added to his sentence.

To keep his sanity, Mr. Win Tin smuggled fragments of brick into his cell and ground them into paste to write poems and philosophy on his cell walls. “I could not bow down to them,” he said in an interview with The New York Times in 2009, the year after his unexpected release.

In one of his most dangerous acts of defiance, he disseminated writing about his plight. In 1996, seven years were added to his sentence after he petitioned the United Nations about conditions in Myanmar’s prisons.

Image Mr. Win Tin, in an undated photo, was released in 2008. Credit... Amnesty International, via Associated Press

Once a year during his imprisonment Mr. Win Tin’s captors offered him a chance to renounce his political beliefs and resign from his party. Each time, he had the same response: a wordless smile. His stubbornness continued after his release. He refused to stop wearing his blue prison shirt, or a replica of it, until all political prisoners were released.