(CNN) -- A Chinese journalist jailed for eight years for leaking government restrictions on reporting is now free.
Shi Tao's early release was announced by the writers' organization PEN International on Saturday -- 15 months before he was scheduled to be freed. Shi is a member of Independent Chinese PEN Center, which advocates for freedom of speech.
Shi made headlines in 2004 when he sent the media restrictions to a human rights group -- an act that China said amounted to "leaking state secrets," PEN said.
What's more, Internet giant Yahoo played a part in his conviction.
In a widely criticized move, Yahoo handed over Shi's e-mail account information, which the Chinese government used in the case against Shi, according to court documents.
The reporting restrictions were over the coverage of the 15th anniversary of the 1989 Tiananmen Square massacre, in which hundreds of pro-democracy protesters were killed in a government crackdown. Chinese soldiers followed orders to open fire on unnarmed civilians.
Official Chinese government figures said the death toll was 241, including soldiers, with 7,000 injured. Rights groups have said the number of dead was likely in the thousands.
Shi was sentenced to 10 years in prison in 2005. It's not clear why he was let go early.
The U.S. Congress led a probe into the case after his conviction.
Yahoo lawyers defended the move to hand over information, saying not doing so would have jeopardized the company's own employees.
"I cannot ask our local employees (in China) to resist lawful demands and put their own freedom at risk, even if, in my personal view, the local laws are overboard," attorney Michael Callahan said in 2007.
Yahoo settled with Shi's family for an undisclosed amount. But the late Rep. Tom Lantos had harsh words for the company.
"It took a tongue-lashing from Congress before these high-tech titans did the right thing and coughed up some concrete assistance for the family of a journalist whom Yahoo had helped send to jail," Lantos said at the time.
Shi was apparently released on August 23, but Marian Botsford Fraser, who heads up the Writers in Prison Committee for PEN, says her organization just learned of it. Botsford Fraser said Shi hasn't communicated directly with PEN but he has spoken with a affiliated group in China.
Botsford Fraser said Shi is currently living with his mother and is in good spirits. But, she added, he has no desire to speak publicly.
Botsford Fraser emphasized that while her organization welcomes Shi's early release, it has many unanswered questions. PEN can only speculate, Botsford Fraser said, as to the timing and rationale of his release. Also unknown is why Shi recently began to receive better treatment in prison.
Of late, authorities even allowed Shi to write, Botsford Fraser said. In October 2010, when he learned that Liu Xiaobo, a Chinese dissident, received a Nobel Peace Prize, he composed a poem which read in part:
Comes from afar, but not to end
Will become a festival for all the unfortunates and their friends."
Shi's release was not covered by Chinese state media.
CNN's Emma Lacey-Bordeaux contributed to this report.