Five days ago, the lawyer representing jailed Chinese dissident artist Ai Weiwei disappeared. He posted a "microblog message" saying he was being followed, then went silent. Now the artist's attorney is back in Beijing, but he won't talk about where he had been or what had happened while he was off the grid.

The attorney, Liu Xiaoyuan, is one of a handful of notable Chinese lawyers who have disappeared since February, according to the Guardian. "Some of those, including Teng Biao, Li Tiantian and Liu Shihui, are still unaccounted for. Others are thought to have had their movements restricted."

Activists say the recent spate of disappearances, including Ai's, bucks a decades-old trend.

Phelim Kine, Asia researcher for Human Rights Watch, said: "China is no stranger to sometimes cyclical periods of increased and easing repression. But when you look at the past 20 years ... there was at least a veneer of due process.

"The victims of enforced disappearances are multiple, because family members have absolutely no idea of the location, safety or future of these individuals."

Ai has been unreachable since April 3, when he was detained at Beijing Airport before boarding a flight bound for Hong Kong. "His friend Wen Tao, 38, driver and cousin Zhang Jinsong, also known as Xiao Pang, 43, accountant Hu Mingfen, 55, and colleague Liu Zhenggang, 49, also remain missing."