Tan was investigating why so many school collapsed in Sichuan
Activist Tan Zuoren, who has been sentenced to five years in prison for "inciting subversion of state power", was a well-known critic of the Chinese government.
The 56-year-old was tried over comments he made on the internet in which he criticised the government for its handling of the bloody crackdown on pro-democracy protests in Tiananmen Square in June 1989.
But Tan's supporters believe that the real reason for the trial was to silence him.
Tan had been a vocal critic of the government in the wake of the massive Sichuan earthquake in 2008, in which nearly 90,000 people died.
In particular, he had questioned why so many schools collapsed in the quake - in many cases when other buildings around them remained standing.
The government admitted that nearly 14,000 schools were damaged in the quake, and there was widespread anger in China that so many children died.
Many said the poor construction of the schools was a result of corruption.
In the months after the quake, bereaved parents complained that they were being prevented from publicly mourning their children, in an attempt, critics said, to keep the issue quiet.
Tan asked internet users and people who had lost their children in the quake to help compile a detailed database of the victims.
He also asked volunteers to help him detail any evidence of poor construction at the schools.
He was in the process of compiling his independent report into the schools when he was arrested in March last year.
Tan's lawyer, Pu Zhiqiang, believes that by exposing the extent of the destruction, he would have embarrassed the government.
"They took out any mention of the earthquake from the verdict because they are afraid of referring to it," said Mr Pu.
Tan's wife, who was not allowed to attend court, described the trial as "ridiculous" and lacking justice.
Artist and fellow activist Ai Weiwei said Tan's crime was "entirely one of speech, of conscience".
"All he did was to publish his personal diary and an investigative report into the deaths of students," he said.
"If he is sentenced to five years in prison for doing that, then nobody is safe in China."