Suspect in Killing of Chinese Student in South Korea Was a TA Who Threatened Students

The man arrested over the killing of a 25-year-old Chinese student in South Korea allegedly threatened other students with delaying their graduation during his time as a university teaching assistant — and, after the killing, reportedly disguised himself as a woman, switched off his victim's phone, and posed as a tipster to mislead police.

The new details emerged Aug. 26, a day after police confirmed the death of the woman, who had returned to the southern city of Gyeongsan on Aug. 14 to collect her graduation certificate after several days out of contact. She was found dead in the residence of a Chinese man in his thirties, surnamed Zheng (郑昌圣), who was arrested on suspicion of murder.

Zheng was not a stranger to the university that connects him to his alleged victim. He worked as a teaching assistant at Daegu Catholic University, where he had once taught a year-long "special topics in neuroanatomy" course, according to a classmate of the victim who spoke to reporters. The most damning account came not from the victim's circle but from a former student blogger who said he had crossed paths with Zheng in 2023. In a widely circulated post, the blogger described Zheng harassing his girlfriend with repeated messages, then — after being rebuffed — threatening that he was "fully capable of making professors ignore you, or even delaying your graduation or blocking it altogether." The blogger said he reported the behavior to the university's international office, and that Zheng later asked him to help smooth things over with a professor.

South Korean media separately reported that Zheng switched off the victim's phone after the killing and disguised himself as a woman while reporting the case, muddying the investigation before detectives identified him. The gang of specifics — a teaching assistant with power over students, a boyfriend-impersonating false report, a victim who had come back to campus only to collect her diploma — gave the case an especially cruel shape on Chinese social media, where it ranked high on Baidu and trended on Weibo across several related topics. "Keep his face in mind, because he'll be back sooner or later," one widely shared post warned, referencing the fact that South Korea has carried out no executions since 1997 and that a life sentence there can, in practice, mean release on parole after two decades.

The case is the second time this summer that the killing of a Chinese national abroad has transfixed Weibo, after a separate abduction in Thailand — but here the alleged perpetrator and victim were both Chinese, and the alleged abuse of a teaching role has focused public anger less on South Korea than on one man's misuse of authority over younger students. Gyeongsan police began formal questioning of Zheng on the morning of Aug. 26, with the investigation centered on motive, the precise sequence of events, and the victim's time of death, as prosecutors weighed a detention warrant.