Authorities in the southern Chinese province of Guangdong have detained a second person linked to a poetry anthology in honor of late political prisoner and Nobel peace laureate Liu Xiaobo, who died in police custody of late-stage liver cancer in July. Peng Heping, a close friend of poet Wu Mingliang, known by his pen-name Langzi, was detained in Guangdong's provincial capital Guangzhou in connection with his friend's "illegal business activity" charge brought by police on Aug. 18. Now Peng, who helped Wu publish an anthology of his own verse last year, is being held under criminal detention on the same charges, writers' group the Independent Chinese PEN Center said, calling for the pair's immediate release. "The Independent Chinese PEN Center was shocked to learn that one of its members, Langzi, whose real name is Wu Mingliang, was detained by Guangzhou police over the publication of a set of poetry volumes," center chief Bei Ling told RFA. "Langzi's friend from the publishing world, Peng Heping, was also placed under criminal detention on Aug. 29 under the pretext of illegal business activity." The Center said in a statement that Wu and Peng were roughly treated, and that their detention contravened their rights to freedom of expression as enshrined in the Chinese constitution. "The right of poet Langzi to exercise his civil rights and freedoms with the publication of the memorial poetry anthology for Liu Xiaobo through the use of fabricated charges is giving rise to a miscarriage of justice," it said. "This will cause serious harm to ... literary creativity and the constitutional rights of Chinese citizens." Guangdong-based rights activist Wang Aizhong agreed that RFA the charges are trumped up, adding that the authorities are having trouble making them stand up, however. "He is implicated in the charges against Langzi," Wang said. "The authorities have accused Langzi of illegal business activity, but they are finding it hard to make them stick." Wu was pursued by "law enforcement from the Haizhu District State Administration for Press and Publications, Radio, Film and Television (SAPPRFT) after he planned to collate poems in memory of Liu, whose death prompted an international outcry over the authorities' refusal to allow him to seek medical treatment overseas. "They need set up a chain of evidence, and so they have brought in Peng Heping, who introduced Wu to his printer," Wang said. "They are being treated as part of the same[case]." Liu Xia back in Beijing? Rights website Civil Rights and Livelihood Watch reported on Sunday that Peng was taken away for questioning on Aug. 29 by officers from the Huazhou police station in Haizhu district of Guangzhou. Police told Peng's wife that she shouldn't worry, because he would likely only receive an administrative sentence of a few days, and said she wouldn't need to hire a lawyer, it said. A printing works connected to Peng was also searched at the same time. Wang said Langzi's detention appears to be connected to Liu Xiaobo's death, rather than the content of his poetry collection, published last year. "His poetry collection ... came out last year, and there haven't been any issues with that since, but I heard that he was involved in putting together an anthology of verse after Liu Xiaobo's death," Wang said. Liu Xiaobo's widow Liu Xia is reportedly back in Beijing after being taken to an unknown location, possibly in the southwestern province of Yunnan, by state security police during the seven-week mourning period following her husband's funeral on July 16. Veteran rights activist Frank Lu, founder of the Hong Kong-based Information Center for Human Rights and Democracy said he had spoken to Liu Xia at the weekend. "Liu, speaking in a weak voice, explained to me that she could not stop taking[her anti-depressants]," Lu told Hong Kong's English-language South China Morning Post at the weekend. "I also asked her to quit smoking, and she promised me that she would smoke less." The paper quoted Liu's friend Ye Du as saying that she had answered the phone when he called her Beijing home on Saturday but was unable to hear who was calling.