Liu, 22, is a fourth-year student in the psychology department at Beijing Teacher's University. Using the pseudonym "Stainless Steel Mouse" (Buxiugang Laoshu), she has written several online essays criticizing the Chinese government.
"Liu Di has done nothing more than use the Internet to express her views," said CPJ executive director Ann Cooper. "We call on Chinese authorities to conduct a thorough and swift investigation into her whereabouts. If she is being detained, CPJ calls for her immediate release."
On November 7, Liu went missing. The following day, security officials came to her house, which she shares with her 80-year-old grandmother, and confiscated Liu's computer, several books, and other personal belongings. Officials told her family that Liu was being investigated for "participating in an illegal organization." Authorities have not offered her family any further explanation as to her whereabouts.
According to China's Criminal Procedure Law, a suspect's family must be notified of the suspect's whereabouts and reasons for arrest within 24 hours of his or her detention.
In one essay, Liu wrote that "my ideals are the ideals of an open society... In my view, freedom does not just include external freedom, but freedom within our hearts and minds." In another essay, according to Agence France-Presse, Liu called on Chinese citizens to stop reading official news and to read only "reactionary" materials.
In her online writings, Liu Di expressed fears of being arrested and said that authorities had called her in for questioning several times prior to her disappearance, according to online accounts written by her friends and acquaintances.
Liu's disappearance came one day before the opening of the 16th Communist Party Congress. During the run-up to the Congress, Chinese authorities escalated a crackdown on free expression and dissent by arresting government critics, closing Web sites, and tightening already stringent control over the official media.
Out of the 36 journalists imprisoned in China, 14 are currently serving time for publishing or distributing information online, according to CPJ's records.