When the streets were still and the shooting had stopped following the violent showdown between protesters and soldiers in June, 1989, the Chinese government began rounding up people it deemed to be criminals. Many were detained and released, but 1,600 people received formal prison sentences.
Now, it's believed that only one person convicted during that era remains behind bars.
We don't have his photo, but we know his name: Miao Deshun. A factory worker from Beijing, he was convicted of arson for throwing a basket at a burning tank. For this seemingly minor offence, he received a suspended death sentence, which was commuted to life in prison a few years later. Miao is not scheduled for release until 15 September 2018.
"He was a quiet person. He was often very depressed," remembers Dong Shengkun, a fellow Tiananmen convict who once shared a prison cell with Miao Deshun.
Everyone interviewed by the BBC who knew Miao describes him as being painfully thin, almost emaciated.
"We had both been given suspended death sentences and we were supposed to have our feet in shackles," Mr Dong says. "I was chained but he wasn't. He said the guards probably thought he was too thin to be able to wear foot chains. He wouldn't be able to walk under the weight of the chains."
Dead or alive?
Beijing's Bureau of Prisons refused to answer inquiries about Miao Deshun, noting they never answer questions from foreign journalists. However, Dui Hua, a US-based organisation advocating the legal rights of Chinese prisoners, says it is highly likely that Miao is the last prisoner with offences dating back to the Tiananmen uprising in 1989.
Of course, it's possible that Miao Deshun died in prison years ago, and the news of his passing has yet to surface. The Bureau of Prisons will only confirm prisoners' status to direct relatives.
But assuming that Miao Deshun is still alive, why did he stay in prison long after most others were released?
Most former prisoners agree, that, unlike most others, Miao refused to sign letters admitting regret for his participation in the Tiananmen protests. He also refused to participate in prison labour, choosing instead to spend his days reading the newspaper in his cell.
- From 1978, China opened up its economy to the world, but Communists maintained total control over politics
- In 1989, hundreds of thousands gathered in Beijing's Tiananmen Square to call for political reform
- Protesters remained in the square for weeks while a power struggle raged within the ruling Communist Party
- Hardliners prevailed and gave the order to remove the protesters by force; hundreds were massacred in nearby streets
"He is the last prisoner because he never admitted he was wrong, he refused to obey regulations and refused to participate in labour through re-education," a former prisoner, Sun Liyong remembers.
Mr Sun now lives in Sydney, Australia. During the day, he works as a labourer on construction sites. In his spare time, he runs a fund devoted to helping victims and former prison inmates with connections to the Tiananmen protests. He says he isn't even sure if Miao is alive.
"I keep in touch with former inmates and every time I ask them if they have heard from Miao. The last time anyone saw him was about a decade ago."
But other former prisoners also blame Miao's long sentence on his lowly status as a worker who became involved in the protests.
"When the jail terms were handed out, ordinary citizens were given harsher sentences," explains another former prisoner, Zhang Baoqun. "The guys with good connections, or those who were protected by certain associations, received lesser sentences."
"No-one spoke up for people like us," Mr Zhang says. "Wang Dan, one of the protest organisers, was only given four years in prison."
"In the early 1990s when [Miao's] families went to visit him, he refused family visits. He doesn't want his old parents to travel so far to see him. Since then, no-one has seen him. Sometimes Miao and I were locked in single rooms at the same time, my cell just opposite his."
"The authorities treated him as if he was insane. I heard they moved him to Yanqing," Mr Dong says quietly. He doesn't know much about the prison, he explains, except that it's very far away.
The BBC drove for hours through the mountains to reach the gates of Yanqing prison, an institution for elderly and mentally ill prisoners. The prison's remote location makes it seem like Miao Deshun has been banished from modern society, far away from the politics of Tiananmen Square.
Former inmates have had varying degrees of success reclaiming their daily lives.
After leaving prison in 2003, Zhang Baoqun has tried a variety of different jobs in an attempt to support his wife and young son, who was born after his release.
Denouncing his time in prison as a "dirty spot" on his record, Mr Zhang questions his actions during 1989.
"I wouldn't participate in something like that again. It was meaningless. You cannot change your country no matter how hard you try," he explains.
Since leaving prison eight years ago, Dong Shengkun has never been able to find a full-time job. Estranged from his wife and child, he lives with his 76-year-old mother, but he has no regrets about his past choices.
"I have a clear conscience," he explains, adding: "So many people sacrificed so much. They didn't sacrifice their lives for today's materialistic society. Chinese people have become richer now but we shouldn't care less simply because we have better lives now."
Mr Dong is stoic when asked about the last prisoner, Miao Deshun's, long incarceration.
"I am not surprised he is still inside," he sighs. "It has been 25 years but the authorities can do anything they like."