HONG KONG — A Chinese government official I know was put under shuanggui, the secretive system of internal Communist Party investigation in which victims are detained, questioned without counsel and sometimes tortured. He was held for several months last year, and he now awaits trial. This midlevel apparatchik in Yunnan Province was responsible for city planning and construction. I don’t know why they targeted him — shuanggui is so opaque. Friends think he was an able official who may have taken a few bribes. But the most probable reason for his travails with the authorities was that his political patron also got in trouble.

I don’t know who his political godfather was, but in the last year a tempest has shaken Yunnan, and indeed, the whole country. A huge number of top officials have been either arrested or placed under investigation. Some have been driven to suicide. Quite likely this official’s political sponsor was one of these people. Whenever a top official falls, people aren’t concerned about what he has done, but with those he might bring down with him.

In the past two years, President Xi Jinping’s anticorruption drive has burnished his reputation with the Chinese media. And some in the international commentariat have also expressed support, and even praise, for Mr. Xi’s campaign. Yet suspicions persist that the crackdown is selective.

In my view, the anticorruption push is more of a Stalinist purge than a genuine attempt to clean up the government. Charges are framed with reference to party regulations, not the law. Investigations are run by K.G.B.-type cadres, not the regular judicial system. China’s media does not report on cases until they are made public, after which there is a barrage of almost identically worded reports used to incriminate the suspect. Most telling of all, the purge has mainly targeted specific party factions, while those groups that support and pledge loyalty to Mr. Xi appear untouched.