A Chinese journalist who was jailed because of incriminating email records provided by Yahoo has been freed by local authorities after serving over eight years in prison.

Shi Tao, a former reporter and editor of a Chinese newspaper, was released 15 months before finishing his 10-year sentence, said humans rights and literature advocacy group PEN International on Saturday. It is unclear why he was released early.

He was arrested in 2004 after sending out an email that detailed upcoming Chinese government restrictions on the local media in the run up to the 15th anniversary of the Tiananmen Square Massacre. The email was sent using a Yahoo Mail account, and its information was posted anonymously on a website based in New York focused on promoting democracy in China.

Yahoo agreed to give up Shi’s email account information to Chinese authorities, who were tracking the source of the information. It resulted in Shi receiving a 10-year prison sentence for leaking state secrets.

In its defense, Yahoo said it was following Chinese laws in handing over Shi’s email records. The company’s actions, however, drew criticism from human rights groups and even U.S. lawmakers, who opened an investigation in 2007 over Yahoo’s handling of the case.

During the congressional hearings, Yahoo apologized for the incident and said it was working to help release Shi.

Since then, Yahoo’s presence in China has greatly diminished. At the start of this month, Yahoo’s Internet portal for the country went offline, as part of a strategy change by e-commerce giant Alibaba Group, which controls the Yahoo brand name in China. Yahoo’s mail and music services for the country have also closed down.

On Sunday, Voice of America reported that Shi had returned home to the Chinese city of Yinchuan, but declined to speak to the media.