Why is a decades-old poisoning case taking Chinese social media by storm?

A surprising topic has dominated Chinese social media over the last few weeks: the story of Zhu Ling, who in 1994 was an undergraduate at Beijing’s prestigious Tsinghua University. "Enthusiastic, intelligent and attractive, she was an active member of the college folk music team, and was already considered by many to be a model student with a wonderful future," recalls the Help Zhu Ling Foundation, which describes itself as a California-based non-profit.

That year, Zhu was stricken by a mysterious illness thought to be caused by thallium poisoning, and speculation soon centered on one of her roommates, Sun Wei, the granddaughter of a high-ranking Chinese official named Sun Yueqi who was rumored to have close ties to former President Jiang Zemin. Questioned but never arrested, Sun reportedly fled to the United States. Much of the anger surrounding the case stems from the belief that Sun’s connections shielded her from a serious investigation.

In recent days, Yao Chen, a Chinese actress who has the most popular account on the microblogging platform Sina Weibo, has written several posts on the case, including one that got forwarded more than 100,000 times (Emily Parker’s recent New Republic article on Zhu has been reposted more than 100,000 times on Sina Weibo as well). More than 100,000 people have signed a petition asking the White House to deport Sun.

So what’s going on? The reappraisal of the case seems to have been triggered by the unrelated poisoning of a student at another prestigious Chinese university in mid-April, and the commentary the incident triggered about a life wasted. But Zhu’s case is more morally ambiguous than the latest episode (for one thing, Sun might not be guilty), and it’s these shades of gray that may be giving the story legs. An article published Tuesday on the Financial Times‘ Chinese website, for instance, channels Socrates in meditating on the Zhu case, the rule of law, and what justice should mean in modern-day China. Prominent Chinese leftist Wu Danhong, whose weibo account is a pun on his name and an expression meaning lawlessness, praised Zhu’s father’s "clear rejection" of the White House petition — and thus his faith in official channels and Beijing’s ability to govern.

Zhu, for her part, is now a "200-pound, paralysed, diabetic, almost-blind woman with the mental capacity of a six-year-old," according to the South China Morning Post. Sun’s whereabouts are unknown, and old cases like these are difficult to solve — especially for a country with as creaky a justice system as China’s. As Hu Xijin, a well-known commentator and editor of the Global Times newspaper, wrote on his microblog, even the O.J. Simpson case never got cracked. This one might not either.