In China's uphill battle against rampant corruption, no other Communist Party agency evokes more fear among officials than the Central Commission for Discipline Inspection (CCDI), the country's top anti-graft watchdog.
The commission's name may sound innocuous, and so does its most potent weapon, known as shuanggui - a two-word abbreviation from a clause in the party's regulations that requires members to explain their so-called disciplinary violations at a specific time and venue.
But those two words have given the commission sweeping powers to indefinitely detain and question any official suspected of wrongdoing.
The process is cloaked in secrecy, and suspected officials are subjected to round-the-clock surveillance and harsh interrogation techniques, while being denied access to any outside contact, including with lawyers and family members.
The confinement may last months or even years, until officials break down or investigators collect enough evidence to cement their case.
Few officials placed under shuanggui are likely to emerge unscathed. Those held on lesser offences may receive demerits or demotions, but in serious cases, officials are stripped of their party membership and turned over to prosecutors for criminal trials.
According to the CCDI, more than 160,000 party members have been punished for disciplinary violations, but it did not say how many had been criminally prosecuted.
Those cases include that of Bo Xilai, formerly a Politburo member and party secretary of Chongqing , and the highest-ranking official to be placed under shuanggui in a decade.
While many mainlanders, angry about rampant corruption, harbour little sympathy for how officials are treated under shuanggui, an increasing number of legal professionals and media commentators have begun to question the secrecy surrounding the process, particularly the harsh interrogation techniques, arguing that they contravene the country's efforts to push for rule of law.
While anti-graft interrogators have shown no intention of lifting the veil of secrecy, a short news story in the Beijing Evening News last month has provided a rare glimpse into how the interrogators go about their business. Ironically, the article was published to pay respect to a 41-year-old interrogator in Beijing who died of a heart attack in January amid a heavy workload of interrogating corrupt officials.
Zhou Lijun, head of the interrogation team in Changping district, had been tasked with investigating a township-level official surnamed Li for alleged corruption.
The suspect was confined to a room with a bunk bed, a table and a chair. On top of conducting the interrogation, Zhou and his team members took turns sitting on the chair in the room to monitor Li in eight-hour shifts, all day and night. Interrogators were forbidden to talk to Li about the case, except when he was being formally questioned, and they were not allowed to leave the room during their shifts.
The routine lasted 18 days and nights before Li broke, the article said, without mentioning what happened to the official.
But Li may be a lucky one. State media regularly report that some officials have committed suicide or died under mysterious circumstances.
The latest example involved the death of an official who was under shuanggui last month in Wenzhou , Zhejiang . Though investigators said his death was accidental, his family members produced photos showing multiple bruises on his body, appearing to indicate he had been tortured. This prompted the Beijing Times to run a commentary urging transparency in the shuanggui system, as well as for it to be governed by the law.