I was delighted by the turn of events. It certainly saved me the trouble of looking for her. "Professor, shall we go out for a cup of tea?" I suggested.

The head of the archive department agreed so we found a teahouse just outside the school and ordered a pot of green tea.

She looked about 40 years old and was surnamed Gao. I was shocked at the huge age gap between her and Qi Sheng so I asked, “Madam Gao, how long were you married to Professor Qi?"

"More than 20 years. In fact, I used to be his student. Although he’s old now, he used to be a handsome and dashing man in his younger days. Back then, everyone around me objected to our teacher-student relationship but at the time, I was as stubborn as mule, my heart set on marrying only him. Alas! I wish I had listened to my family’s advice. He had the sort of paranoid personality that made it hard for him to get ahead. Then later on, he did such a terrible thing that even I couldn't believe at first. He destroyed my life. As the wife of a criminal, I was no longer allowed to teach and I was only given this job in the archives after begging repeatedly."

Having shared as much, Madam Gao sighed deeply, her hands wiping away the tears on her face. I couldn’t help but utter a few words of consolation.

"Was Professor Qi close to any of his students?" I asked.

Without a second thought, Madam Gao replied, "Yes!"

The student was Wang Yizhou, a boy very interested in mechanical engineering. He often met up with Qi Sheng to discuss engineering problems and attended all of his classes, even if he hadn’t signed up for them.

Wang Yizhou was a pitiful orphan who grew up tragically. Every Lunar New Year, Qi Sheng invited him home for the reunion feast, after which, they would fiddle with their little inventions together. Madam Gao used to tease Qi Sheng about their close relationship and even suggested adopting him as their son since he liked the boy so much.

The boy reciprocated Qi Sheng’s fondness for him with the same love and respect. When Qi Sheng was arrested by the police, he knelt at the school gates for a long time after the police vehicle left. After he graduated and started working, he often visited Madam Gao until she finally divorced Qi Sheng and remarried.

After listening to her narrate the past, I rummaged through a box of student files, all of which were arranged alphabetically, and found Wang Yizhou at once. The picture on his file showed a gentle-looking boy with sullen eyes behind a pair of glasses. At the sight of this face, an alarm bell went off in my head. My intuition told me that this man was the murderer!

"Officer, it’s been ten years since the case was concluded,” said Madam Gao. “Why are you suddenly investigating the case again? Did this kid do something?"

"Why would you think that? Does he seem like the kind of person who would commit a crime?” I asked in return.

"Teachers have that special sixth sense when it comes to judging people. I could tell that this kid was a bit paranoid like my ex-husband."

"It’s not surprising that many people are paranoid after hitting the 80s and 90s,” I remarked.

But Madam Gao shook her head. "He’s not just paranoid,” she explained. “How should I put this…. he has a history of mental illness."

Hearing this, my suspicions about Wang Yizhou further solidified so I asked her what illness he had.

"It's not anything serious like schizophrenia. He had a contradiction with my family and in a fit of pique, slammed his head into the wall. When his family sent him into a mental hospital, he made all sorts of trouble inside. I heard he went off the rails and bit several nurses! In truth, that so-called mental hospital was of little help. It was more like a prison to isolate the mentally ill from the rest of society. The more disobedient they behaved, the more severe the torture. He was treated with electroconvulsive therapy and behavioral therapy by doctors and force-fed sedatives for more than half a year. However, I could tell that his mental state was more unstable after he left that hellhole."

"Family? Didn't you say he was an orphan?” I asked.

"The boy’s situation was a bit complicated,” she replied. “As a child, he was an orphan but later, his father emerged out of nowhere and adopted him."

I asked her what Wang Yizhou's father did for a living but Madam Gao was unsure. I remember that the three victims supposedly killed by Qi Sheng were the dean, a teacher who abused children, and an unscrupulous liquor dealer who made and sold fake alcohol.

I pulled out a piece of paper, wrote down their names and asked Madam Gao, "Do you know these three people?"

"I’ve heard of them,” admitted Madam Gao. “Back then, when Qi Sheng was tried in court, I attended the hearing. They are the victims from ten years ago, aren’t they? But I only knew the first one personally, that is, the former dean of our school. Qi Sheng usually left him to his own devices even when he was up to no good. So the dean switched to more despicable means and plagiarized one of his academic papers. A big part of why Qi Sheng was so greatly stimulated was definitely due to this person."

I ended the conversation by thanking her and returning all the other student files except for Wang Yizhou's.

By this time, it was already noon and Dali began to complain about hunger. I was so busy investigating that I had forgotten about lunch entirely. We simply picked a nearby noodle shop and ordered two bowls of beef noodles. While waiting for our noodles to be served, I phoned Xiaotao and asked her how she was doing.

"Not good,” a dejected voice sounded from the other end of the line. “We’ve sifted through all the employees of the three slaughterhouses but we didn't find anyone who matched those characteristics."

"What about employees who left?" I asked.

"Do you think I’d forget about that?” Xiaotao gave a weak, watery laugh. “I even went through the list of employees laid off 20 years ago but I came up empty!"

"If he doesn’t work in a slaughterhouse, could he be a self-employed butcher in a market?" I asked.

"That’s too wide a range to go searching,” lamented Xiaotao. “Sigh, looks like we’re all headed for sleepless nights!"

"I did manage to find something here,” I said, trying to cheer her up. “Could you check someone’s household registration information for me?"

"Do you have an ID number?” she asked. “Tell me and I'll send the information to your email later."

After scarfing down our noodles, I received Wang Yizhou's household registration information from Xiaotao. The columns that read, "Mother" and “Father” were filled in as deceased. I thought the man who had suddenly popped out of nowhere was an adoptive father but when I looked at his father's date of death, I noticed that it was ten years ago.

I couldn’t help but exclaim in surprise at his name. "What a coincidence!"

"Why are you surprised?” Dali looked at me puzzledly. “It's not like you at all. Aren’t you usually calm and collected?"

"Here’s a great discovery–the third victim killed ten years ago was Wang Yizhou's biological father!" I cried.

Dali snatched the phone out of my hand and glanced at the information. "Why do the father and son have different surnames?" he asked.

"Wang Yizhou took his mother's surname,” I stated. “Both mother and the son were probably abandoned by the father who came back years later to adopt him."

"What a heartless man!” Dali spat his tongue. “He kowtowed in gratitude to the man who murdered his father!”

"I'm afraid it's not that simple!" I shook my head.

The first victim was the dean, the second was a teacher at the orphanage who abused children, and the third was Wang Yizhou's biological father, all of whom had an intersection with Wang Yizhou. Back when Qi Sheng confessed, Wang Yuanchao said he had a gut feeling he wasn’t the murderer from the very beginning.

At this point, the truth was imminent–Qi Sheng didn’t kill those men, Wang Yizhou did! Qi Sheng had taken the blame for his beloved student!

Ten years ago, the three victims were Wang Yizhou's experimental objects. Ten years later, he had already turned himself into Storm Punisher, a murderer with experienced and refined methods.

After hearing me out, Dali’s eyes widened in shock. "That old man is pretty selfless. Why would he protect a murderer?"

"Perhaps he didn’t want his favorite student’s future to be destroyed,” I speculated. “These are just my own conjectures but it's not difficult to prove them. Catch Wang Yizhou and we’ll know the truth! Come on, let's go explore this sadistic murderer’s thought process."