Updated

An activist who campaigned for Inner Mongolia's independence from China appears to have been released from prison after a 15-year term but is likely still being detained somewhere by state security, a relative said Monday.

While separatism among Mongolians living in Chinese-controlled Inner Mongolia is not well known, it's a hot-button issue for China's government, which fears the spread of the violent ethnic unrest that has hit Tibet and Xinjiang in recent years.

The 56-year-old activist Hada, who like many ethnic Mongolians uses just one name, was scheduled for release from prison last Friday but has not surfaced, said his sister-in-law, Naraa.

Naraa said a compact disc that contained five digital photographs of Hada with his wife and son was delivered to her on Sunday by a man who refused to identify himself. The photographs appeared authentic and current, she said, and showed the family apparently eating a meal together in a room that did not look familiar.

"We felt a little happier when we received the photos, for a while," Naraa said. "But until now he still hasn't come back and he hasn't phoned us yet, so we think he probably still doesn't have his freedom yet."

Hada helped found the Southern Mongolian Democratic Alliance seeking to establish an independent nation in Inner Mongolia. His bookstore in the Inner Mongolia capital of Hohhot became the center of the movement, and more than 200 people demonstrated in front of the store on Dec. 30, 1995, singing and holding up images of Genghis Khan, the legendary 13th-century Mongolian conqueror.

He was jailed in 1996 on charges of separatism and spying.

Calls to the No. 4 prison in Chifeng city, where Hada served his prison sentence, and the Inner Mongolia Regional Detention Center in Hohhot city, rang unanswered Monday.