Jia Jia has been freed here and had met his wife, his lawyer Chen Jiangang told media.
"It was really a big misunderstanding to hold Jia Jia for 10 days thinking he was somehow involved in some letter," Radio Free Asia (RFA) has quoted lawyer Chen Jiangang as saying.
The columnist in Wujie News, which is a website funded by e-commerce giant Alibaba and the provincial government of Xinjiang, went missing from Beijing airport on March 15 while boarding a flight to Hong Kong.
Yesterday, the BBC reported quoting an unidentified staff member at Wujie that those "taken away" include colleagues who work directly for the website and another 10 people who work for a related technology company.
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Police suspect that he drafted the letter, Chen said.
"But in the case of China, a misunderstanding can embroil a whole clan," he said.
Jia's social media account, which had been silent since he went missing, carried a brief note saying "thank you, everyone" for showing concern over his case, according to the RFA report.
The anonymous letter while appreciating Xi's sweeping anti-corruption drive has accused him of promoting "personality cult, not allowing 'rash opinions of central leadership', creating a 'one voice party' method" disregarding the collective leadership principle.
Although quickly deleted by the authorities, a cached version can still be found online.