By the time building staff gained access to Liu Hanbo’s apartment on Oct. 31, she showed no vital signs. Doctors found that Liu, a history teacher at Xinzheng No. 3 High School in the central Henan province, had suffered a heart attack which led to her “sudden death.”

The conclusion shocked her family. According to her husband Chen Ming, Liu had always been in good health, and in more than 20 years of teaching, no underlying heart diseases had ever been detected in physicals.

The day after her body was found, he came across videos her students had posted of her last online class. That’s when he learned that since mid-October, a group of users calling themselves baopo lieshou, which literally translates as “bombers and hunters,” had repeatedly gatecrashed her online classes on DingTalk — a conference call app used in online classrooms.

Over the course of several days, they barged into her online classes where they shared their screens and unmuted their mics to hurl abuse at Liu, played loud music, and spammed the chat window.

The hunters did it again on October 28 — the day doctors said she died.

On Nov. 2, Liu’s daughter alleged on Weibo, China’s microblogging platform, that her mother died of cyberbullying at the hands of those trolls. The post went viral, was shared over 200,000 times, and sparked an outcry online.

The same day, Xinzheng City’s education bureau announced that authorities had ruled out foul play in her death but that they were looking into reports that she had been cyberbullied.

Over the last two years across China, Liu Hanbo’s case isn’t an isolated one. And the surge in online classes in the wake of the COVID-19 pandemic has further burdened teachers, particularly those who struggle with software.

Colleges have fallen victim, too. On Sept. 5, trolls disrupted online classes at Shenyang Urban Construction University in the northeastern Liaoning province. They unmuted themselves and then wrote out “I love you, teacher” while blasting music.

The last class

Liu’s husband Chen Ming was the first to sense that something was amiss.

He worked in Zhengzhou, a 90-minute drive from their home in Xinzheng, and last video chatted with Liu at noon on Oct. 28. All seemed normal until he failed to get in touch with her over the next two days. The school said they couldn’t reach her either.

At around 6 a.m. on Oct. 31, Chen called her again. No answer. When the school contacted him to ask if he knew anything, he quickly called police and the property staff at her apartment building.

Like many senior teachers thrown into online classrooms across China, Liu wasn’t very comfortable with the technology involved. According to Li Yuan, a tenth grade student, she didn’t know how to share her screen on the computer, so she livestreamed her desktop using her phone camera instead.

In the two days Liu went incommunicado, school officials noted in a faculty group chat that Liu missed online classes for the second consecutive day on Oct. 30. She had another class at 8 a.m. the next day.

Li reached out to her. No reply. At 8:02 a.m., a student wrote in their class app DingTalk: “It’s your class now, teacher.” A few minutes later, the head teacher told Li to proceed with an independent study session.

Li vividly recalls the last class her teacher held online.

They were scheduled to do timed problems from 8:10 p.m. to 9:10 p.m., during which 200-plus students across four classes would work on topics Liu selected from their practice booklets.

The class quieted down once they had their assignments, with heads bent over their booklets. Everybody kept their cameras on, but only Liu and a few other students stayed unmuted.

At 8:16 p.m., trouble began. Strangers suddenly started streaming in, with usernames like “Ji Nitaimei” or “Chicken Beautiful” — referring to a popular Chinese song; “Menglei” — the avatar of professional e-sports player Xiao Minhui; and “Ultimate Hunter Menglei.”

The unusual names immediately gave away that they were interlopers, since legitimate students have standardized formats: their grade in school, their school number, and their real name.

Some students immediately started recording their screens, and videos Beijing Youth Daily obtained show the trolls playing what they called a “battle cry” while verbally abusing Liu.

Students who were interviewed recall feeling disoriented and sought help from the teacher in the next classroom, surnamed Niu.

Amid the clamor, Niu told Liu at 8:17 p.m.: “Do you want to make me the host, Ms. Liu?” Liu replied, “Do I exit out?”

At that point, the music played again at ear-splitting volumes. Then Chicken Beautiful began targeting Niu as well, using a voice changer as they heaped more obscenities. Referring to her surname Niu, which means strong or brilliant, one of them said: “Think you are tough as your surname?”

Li said she mustered up the courage to unmute herself, but nobody other than Niu said anything, so she ultimately stayed quiet. “Why didn’t we push back?” she rues, blaming herself. “If I had yelled back and put a stop to it, maybe this tragedy wouldn’t have happened.”

The profanity-laced hijacking lasted for about five minutes before Niu forcibly ejected them, allowing the class to finish on time. Li recalled how Liu’s voice had trembled as she told them, “Focus on your assignment. I’ll be checking them after class.”

This was the last sentence she heard her teacher say.

After class, Li found out from her peers that Niu had broken down in tears too.

Intrusion

The miscreants were familiar. Li had noticed the same profile pictures and screen names when the same group hijacked Liu’s classes on Oct. 12 and Oct. 21. Another student noticed that they seemed to occur only when all four classes were studying together.

On Oct. 12, the intruders had just played music, and Liu managed to kick them out with help from the students. Nobody admitted to having anything to do with the incident.

After Li spoke with a couple of classmates, they decided to have Liu make the room private and invitation-only for their next session. Yet somehow, the trolls still managed to access the meeting ID and password.

On Oct. 21, they went a step further, sharing their screens and streaming pornographic content.

Recordings that have been obtained show Liu assigning tasks at 8:18 p.m. that night when music abruptly started to play. “Who’s that?” she asked, but after getting no answer, she resumed her work. Then the music changed. A user named Menglei took over their screen and typed, “What are you looking at? It’s Menglei.”

Liu tried to maintain order and asked, “Who is this? This page popped out of nowhere, and there’s all this noise.”

“What are you looking at?” the troll continued, undeterred. “I’m Menglei. Thanks for sending me your meeting ID.”

At 8:25 p.m., Niu logged in and reminded Liu to remove the troll, to which Menglei wrote, “What are you bitching about?”

By that time, Liu still had enough strength to reply, “I’ll find out who you are.” Unable to watch any longer, some of the students unmuted themselves and said, “Teacher, they’re not students here. We don’t know who invited them, but somebody leaked the meeting ID.”

At 8:27 p.m., Liu said shakily, “I’ll just photograph each page and see if I can locate the hacker.” The troll then escalated their abuse, and they taunted her by saying, “So you want to know who shared [the meeting ID], huh?”

Liu’s husband Chen Ming, who was at home that day and had witnessed it all, remembered Liu being angry and emotional yet determined to finish out her class. But Chen urged her to stop, so she ended the session 36 minutes early. He had pegged it as a random incident.

On the trail

Led by the head teacher, Li and other students began to collect evidence after Liu’s death. By the end of Nov. 1, they had uncovered 12 “suspects.” Li sent a friend request to all of them. One accepted: “Menglei.”

Li was so agitated when she saw it that she almost cried, and her hands trembled as she typed out a message to the purported ringleader. Menglei greeted Li and then went silent.

The headteacher helped her calm down and then asked her to try again, to see if she could worm more out of them and uncover the group.

Four suspects ended up accepting her friend requests. With an opening offer of 100 yuan ($14) per “bomb session,” she started chatting with them.

One of the suspects, whose IP address identified them as being in Urumqi, in northwest China’s Xinjiang Uyghur Autonomous Region, warned her, “Don’t hijack online classes; it’s unethical.” He also said he was innocent and had been pulled in by others. “If you wanted to find [class hijacking] services like that, there are many available on any short video app.”

The objective of “bombers” is simple: disrupt classes and insult teachers. When Beijing Youth Daily contacted one user who had previously trolled online classes, they said they would do it for free and that they also screen capture themselves to keep a record.

Moreover, “Menglei” is a common username for such trolls. It refers to a well-known e-sports player in Honor of Kings, one of the most popular mobile games in China.

As early as Sept. 6, however, the actual Menglei — whose real name is Xiao Minhui — had taken to Weibo to urge that such pranks “cease immediately.”

The trolls also frame students to sow more discord. One intruder wrote to Liu, “Want to know who gave us the meeting ID?” Then, they named a specific student.

According to screenshots that Liu’s family posted on Weibo, this student had tried to chat with the troll, who subsequently named that student again. According to the class, the defamed student was a good person and would never do such a thing, though the incident had definitely inflicted emotional harm on that person. Li also emphasized that it was a false accusation.

Despite her best efforts, Menglei’s actual identity remains unknown. “DingTalk doesn’t allow you to view their district or school,” she explains.

Fu Jian, the head of the Zejin law firm in Henan, believes that the case may constitute the crime of “picking quarrels and provoking troubles,” or potentially the crime of serious public insult.

According to the latest updates, Liu’s daughter posted that the Zhengzhou authorities and the education bureau were “highly concerned” about the matter. On the morning of Nov. 3, DingTalk had also said that relevant personnel were looking into the incident and that they plan to cooperate with police investigations.

Reported by Wu Lin, Tian Jiayi.

(Li Yuan and Chen Ming are pseudonyms used to protect the privacy of the interviewees.)

A version of this article originally appeared in Beijing Youth Daily. It has been translated and edited for brevity and clarity, and published with permission.

Translator: Katherine Tse; editors: Zhi Yu and Apurva.

(Header image: Visuals from Weibo and Anastasia Borodavkina/VCG, reedited by Sixth Tone)