Beijing (CNN) -- Chinese authorities released prominent human rights activist Hu Jia Sunday, days after freeing renowned dissident artist Ai Weiwei.
"A sleepless night -- Hu Jia arrived at home at 2:30. He's safe and I'm very happy," Zeng Jinyan, Hu's wife, said in a Twitter post Sunday morning. "He needs to rest for a while."
Hu, 37, denounced China's human rights record in a series of articles ahead of the 2008 Beijing Olympics and was later sentenced to 3.5 years in prison for "inciting to subvert state power." Ai, the conceptual artist turned government critic, was released Wednesday on bail after authorities detained him for nearly three months for tax evasion, the state-run Xinhua news agency reported.
The seemingly positive news, however, has been dampened by the noticeable silence of both once-outspoken activists.
While Ai declined to answer questions from reporters outside his home early this week, police Sunday guarded entrances to Hu's apartment compound and patrolled surrounding streets. Zeng, his wife, appeared unreachable via phone or the internet.
Zeng told CNN Friday that authorities started 24-hour surveillance on her several days before Hu's expected return. In an interview last December, she predicted a virtual prisoner's life for the couple in their housing complex, called Freedom City.
"Hu Jia told me that he won't change, and police told him they may put him under house arrest in that case," she said. "I'm prepared for it."
"As long as there's no democracy or the rule of law in China, our situation won't change at all."
Last year's Nobel peace laureate Liu Xiaobo, also a rights activist, was convicted of the same crime as Hu. Liu is still serving an 11-year jail term.
Activists say the Chinese government, worried about potential uprisings inspired by the Arab Spring, has been increasingly tightening its grip on freedom of expression, targeting not only political dissidents but also intellectuals and artists.
Guo Jian said he has noticed such chilling effects from his studio at the Songzhuang art village, not far from Hu's home.
The veteran artist has been working on a startling installation piece that shows the very symbol of state power being bombed and razed. In the still-untitled diorama, model warplanes hang by thin threads fly over a miniature Tiananmen Square. The heart of Beijing is dotted with bulldozers and tanks, with the iconic Tiananmen Gate and Chairman Mao's mausoleum smashed and half-destroyed.
"The police have sent someone to say, don't show your work or don't let other people know about it," he said. "They're really worried about what I'm doing."
Guo, 48, says for the first time in his 20-year career, police now visit him regularly and plainclothes agents sometimes shadow him on the streets.
Pointing to his unfinished diorama, Guo says the authorities' outdated mentality and methods -- silencing perceived dissent through intimidation and detention -- only reinforce the message in his work: the potentially explosive consequences of suppressing people's voices for too long.
While he feels heartened by the release of fellow-artist Ai and activist Hu, Guo remains concerned about the current crackdown and doesn't see it ending anytime soon.
"Even though we got someone back, the fear is there," he said.