godfather of surgery

Chapter 1391 This is the kind of case we fear most

On Friday morning, Dr. Yuan called again, and Yang Ping called Zaxi to his office and put the call on speakerphone.

"Professor Yang, the test results for the book pages are in." Dr. Yuan's voice held a suppressed excitement. "We detected organophosphate residues on some of the books on the deceased's bookshelf. The concentration wasn't high, but it was definitely present. Moreover, we also detected toluene and xylene residues on the pages of these books."

Yang Ping paused for a second: "Which books?"

"It's mainly those books on the second row of the bookshelf, about twenty or so. They're all chemistry books, some are textbooks, some are monographs. Every single one has residue, but the concentration is unevenly distributed, with the highest concentration at the edges of the pages and lower concentration in the middle."

Yang Ping asked, "What are the fingerprint test results?"

"The results also came back. Trace amounts of organophosphates and toluene residues were detected in the fingerprints of the deceased's right index and middle fingers. The levels were extremely low, but enough to prove that he had been in contact with these substances."

Yang Ping remained silent for a long time, then he said something in a very soft voice, but Zaxi could tell the weight in it: "Someone tampered with those books."

On the other end of the phone, Dr. Yuan asked, "Professor Yang, who do you think did this?"

This shouldn't have been a forensic issue; it should have been the responsibility of the investigating police officers. However, Dr. Yuan was also very curious and wanted to continue analyzing the case following Yang Ping's line of thought.

Yang Ping did not answer directly, but asked, "Besides Professor Zhou, who else would read those books?"

Dr. Yuan said, "We are investigating. What we know so far is that Professor Zhou's study is usually locked, and only he has the key. His students say that he never lets anyone into his study."

Yang Ping said, "That means that to access those books, either Professor Zhou himself or someone who could get the key would have to do so. Professor Zhou wouldn't poison his own books, so the murderer is someone who could get the key."

Dr. Yuan said, "Understood. We are investigating everyone who may have had contact with the key or who may have given him the book."

After hanging up the phone, Yang Ping leaned back in his chair and closed his eyes.

Zaxi couldn't help but ask, "Professor Yang, why did the murderer use such a complicated method? Why didn't they just use poison?"

Yang Ping opened his eyes and looked at him: "Because direct poisoning will be discovered, poisoning tea will be detected in an autopsy. Poisoning food will also be detected. But with this method, the poison is absorbed through the skin in small amounts over a long period of time, making it difficult to trace the source in an autopsy. If we hadn't noticed that the books were too clean, if Dr. Yuan hadn't noticed the pigmentation on the fingertips and consulted us, this case might have been classified as sudden death."

He paused, then added, "There's another point. This kind of murder requires the killer to have a deep understanding of chemistry, to know the toxicity mechanism of organophosphates, to know the permeation-enhancing effect of organic solvents, and to know which books Professor Zhou would repeatedly read. This is not something an ordinary person can do."

Zaxi is now very excited: "You mean, the murderer might be someone from the chemistry department?"

Yang Ping did not answer, but his silence itself was the answer.

In the afternoon, after finishing his work, Zaxi reorganized all the clues from the past few days.

He drew a timeline in his notebook, just like organizing a patient's medical history:

Six months ago: Professor Zhou began to lose weight and become silent, and his blood cholinesterase level began to drop (3800).

Four months ago: My blood cholinesterase level dropped to 2100, and pigmentation began to appear on my fingertips.

In the past week: I received threatening letters.

Three days ago: Death! Pupils were extremely constricted, fingertips were pigmented, trace amounts of organophosphates were found in the teacup, and toluene and xylene residues were found on the shirt cuffs.

Yesterday: Residues of organophosphates, toluene, and xylene were detected on the book pages, and trace amounts of residues were detected in the fingerprints.

He connected these clues and formed a preliminary hypothesis:

Someone applied a solution of an organophosphate compound dissolved in toluene/xylene to the chemistry books Professor Zhou frequently consulted. Each time Professor Zhou turned the pages, his fingertips came into contact with this solution. The organic solvent damaged the skin barrier, allowing the organophosphates to penetrate the skin. Long-term exposure led to chronic organophosphate poisoning—weight loss, personality changes, a persistent decrease in cholinesterase, and pigmentation of the fingertips. At some point, a single exposure to a large dose, perhaps from prolonged reading, triggered an acute poisoning attack, causing extreme pupil constriction, respiratory depression, and death.

The trace amounts of organophosphates detected in the teacup were likely pesticide residues naturally present in the tea leaves and were unrelated to the case—something the murderer hadn't anticipated.

If this hypothesis is correct, then the murderer would need to meet several conditions:
First, they must have access to Professor Zhou's study key or books. Second, they must have sufficient chemical knowledge to understand the toxicity of organophosphates and organic solvents. Third, they must have access to organophosphate compounds and organic solvents. Fourth, they must understand Professor Zhou's reading habits and know which books he frequently consults. Fifth, they must have the motivation.

The first four conditions all point to the same type of people: those around Professor Zhou, especially those in the Chemistry Department.

Zaxi wrote this conjecture down in his notebook.

Who is the murderer?

Zaxi's curiosity was piqued, and he found this kind of reasoning to be an extremely interesting thing.

On Friday afternoon, Zaxi showed Yang Ping his compiled conjectures. Yang Ping sat at his desk, flipping through Zaxi's notebook page by page. He read slowly, lingering on each page for a long time, sometimes pausing to think, sometimes frowning.

About twenty minutes later, Yang Ping closed his notebook and placed it on the table. He didn't comment on Zaxi's speculation, but instead said something that surprised Zaxi: "Go to bed early tonight, and come with me to Nandu University tomorrow morning."

Zaxi was taken aback: "Go to Nandu University?"

Yang Ping nodded: “We’re going to see someone, Professor Zhou’s student, not just Li Xiong. We need to understand Professor Zhou, his personality, his habits, his interpersonal relationships, and what has happened to him in the last six months.” He paused, looking at Zaxi, “Your speculations are logically sound. But logical soundness doesn’t equal factual soundness. We need more evidence.”

“Zaxi, we could have just provided Dr. Yuan with some clinical knowledge consultation, but the reason I let you get so deeply involved in this is because I want you to know that curiosity is very important for researchers. You must protect your curiosity and never stifle it. Follow it and you will tirelessly solve one mystery after another. If you do this in your studies, you will grow very quickly.”

Zaxi nodded; he understood what Yang Ping meant.

At eight o'clock on Saturday morning, Yang Ping and Zaxi got into Dr. Yuan's car. This time, the driver was Lao Yu, an old detective who was in charge of the case and had brought with him. Dr. Yuan sat in the passenger seat, his expression much more serious than a few days ago. Zaxi noticed that he was holding a new document with the word "Confidential" printed on the cover.

"Dr. Yuan, have you made a new discovery?" Yang Ping asked.

Dr. Yuan handed over the documents: "Last night, Lao Yu investigated Professor Zhou's social connections overnight and discovered some interesting things." His tone was calm, but Zaxi could sense the tension hidden within it.

Yang Ping opened the document, and Zaxi leaned over to look at it together. The first page contained Professor Zhou's personal information: Zhou Huaijin, male, 62 years old, professor and doctoral supervisor in the Department of Chemistry at Nandu University, specializing in asymmetric catalytic synthesis. He has received one second-class National Natural Science Award and numerous provincial and ministerial-level science and technology awards. He has published over 180 papers in domestic and international academic journals and has supervised 23 doctoral students and 31 master's students.

The second page begins with his student list. Zaxi glanced at it; it was a dense list of names, followed by graduation year, thesis title, and current workplace. He saw Li Xiong's name; he graduated with his doctorate in 2018 and now teaches at the university, managing Professor Zhou's laboratory after his retirement.

Dr. Yuan's voice came from the front row: "Professor Zhou has many students, most of whom went to universities or research institutes, and a few went to companies. They are all doing well, but there is one person who is very special."

Yang Ping turned to the third page. On that page, a name was circled in red: Chen Wei, male, PhD graduate in 2009, dissertation titled "Design and Synthesis of Novel Chiral Phosphine Ligands and Their Application in Asymmetric Catalysis." The post-graduation destination section stated: self-employed, currently the founder and chairman of Weide Pharmaceutical Technology Co., Ltd.

"Chen Wei!" Yang Ping read the name aloud.

Dr. Yuan said, "Yes, Chen Wei was one of Professor Zhou's most outstanding students in his early years. During his doctoral studies, he published two papers in JACS and one in Angewandte, which is quite an achievement in the field of organic chemistry. After graduation, he did not go to academia, but went into business and founded Weide Pharmaceuticals, which synthesizes and sells pharmaceutical intermediates. The company has grown very large and is now valued at over one billion yuan."

Yang Ping continued reading. The next few pages of the document contained an investigation into the relationship between Chen Wei and Professor Zhou. Zaxi's heart suddenly raced when he read a few lines: "In the early stages of his business, Chen Wei repeatedly returned to the university seeking technical support from Professor Zhou. Professor Zhou transferred some of his research group's findings to Chen Wei's company, and the two parties signed a technology transfer contract. In 2015, a dispute arose between the two parties over the technology transfer fee; Chen Wei sued Professor Zhou, but later withdrew the lawsuit. Afterward, their relationship deteriorated, and they had no further contact."

After reading it, Yang Ping closed the document without saying a word.

Xiao He said from the front, "Professor Yang, we also checked the threatening letter that Professor Zhou received a week before his death, but we couldn't find its source."

These were originally supposed to be said by Lao Yu, but perhaps he felt that Dr. Yuan was more familiar with Professor Yang, so he had Dr. Yuan say them on his behalf.

Yang Ping narrowed his eyes slightly: "What products does Chen Wei's company mainly produce?"

Dr. Yuan said, "Pharmaceutical intermediates, especially chiral pharmaceutical intermediates. We checked their product catalog and found many kinds of organophosphorus compounds."

Yang Ping's eyes flashed: "Organophosphates?"

“That’s right!” Dr. Yuan said. “Chiral organophosphorus compounds are commonly used ligands or catalysts in the synthesis of chiral drugs. Chen Wei’s company has several products that are organophosphorus compounds.”

Yang Ping didn't say anything more, leaned back in his seat and closed his eyes. Zaxi knew he was thinking.

There's a saying circulating at the Sanbo Research Institute: "We're not afraid of how difficult the cases are, we're afraid of Professor Yang squinting." If Professor Yang closes his eyes to rest, the problem will be easily solved when he opens them again.

The main building of the Chemistry Department at Nandu University is a gray-white building constructed in the 1980s, and it looks quite old. A huge sycamore tree stands in front of the building, its leaves already beginning to turn yellow. Dr. Yuan parked his car downstairs, and the four of them got out and walked into the building.

Li Xiong was already waiting at the door. He was wearing a dark blue shirt today and looked more energetic than last time. He led them up to the third floor and into a conference room. The conference room wasn't large, with a long table, a dozen or so chairs, and a whiteboard hanging on the wall.

"Professor Yang, what would you like to know?" Li Xiong sat down, looking somewhat nervous.

Yang Ping sat down: "Officer Yu should ask these questions. I'll just listen from the side."

Officer Yu asked, "Li Xiong, how many years have you been working with Professor Zhou?"

Li Xiong said, "I majored in Chemistry at Nandu University for my undergraduate degree. I worked in Professor Zhou's lab for my graduation project during my senior year, and then pursued my master's and doctoral degrees for a total of seven years. After graduation, I stayed at the university, and another five years have passed since then. In total, I've been with Professor Zhou for twelve years." Officer Yu nodded, "Twelve years is not a short time. You must know Professor Zhou very well."

Li Xiong lowered his head, remained silent for a while, and then said, "I thought I understood. But now... I'm not sure anymore."

Officer Yu looked at him and said, "Tell me about Professor Zhou."

Li Xiong looked up, thought for a moment, and said, “Professor Zhou is a very meticulous person. He is extremely strict with experimental data, and every piece of data must be repeatedly verified and confirmed to be correct before it can be written into the paper. He also has high expectations for his students, and it is common for papers to be revised more than ten times. But he is not the kind of teacher who is so strict that he is frightening. He is very gentle, never raises his voice, and criticizes people in a very calm way.”

He paused, then said, "But in recent years, he has changed a lot."

Officer Yu asked, "How did it change?"

Li Xiong said, "He started becoming more and more silent about five or six years ago. Before, he would have lunch with the students, chat, and joke around. Later, he didn't talk much. He would come to the lab to do experiments and leave as soon as he was done. When you talked to him, he would just nod or say 'uh-huh'."

Officer Yu asked, "What do you think is the reason?"

Li Xiong hesitated for a moment, then said in a low voice, "I think it has something to do with Senior Brother Chen Wei."

Officer Yu's expression remained unchanged, but Zaxi noticed that his fingers twitched slightly.

Li Xiong said, "Chen Wei was Professor Zhou's most outstanding student in his early years. I heard from my fellow students that when Chen Wei was in the lab, Professor Zhou valued him highly and taught him almost by hand. Chen Wei was indeed smart, did well in experiments, and wrote excellent papers. Professor Zhou felt that he was the one who could succeed him. Later, when Chen Wei graduated and wanted to start his own business, Professor Zhou was reluctant to let him go, but he still supported him and transferred several of his research results to him."

He paused, his voice lowering slightly: "But later, the two had a falling out over the technology transfer fee. Chen Wei sued Professor Zhou, claiming that the technology Professor Zhou transferred was problematic, causing his product development to fail, and demanded compensation. Professor Zhou was heartbroken; he felt betrayed by his student. Although Chen Wei eventually withdrew the lawsuit, their relationship was completely over."

Officer Yu asked, "After that incident, how did Professor Zhou's relationship with the other students change?"

Li Xiong thought for a moment and said, "On the surface, nothing seems to have changed, but I can sense that he no longer trusts his students as much as before. He no longer engages in in-depth conversations with his students, no longer shares his thoughts with them, and he has shut himself off."

Officer Yu was silent for a moment, then asked, "Has Professor Zhou done anything unusual in the past six months?"

"For example, has he paid special attention to certain books? Or has he said anything strange? Excuse me, let me interject." Yang Ping added at this point.

Li Xiong thought for a moment and said, "Books... he does often take books from the bookshelf to read. But I'm not sure exactly which books they are. He has his own bookshelf in the corner of the lab, which is filled with his frequently used reference books."

Yang Ping's eyes flickered slightly: "His bookshelf? In the lab?"

“Yes!” Li Xiong said, “There’s a metal bookshelf against the wall in the lab. There are about forty or fifty books on it, all of them chemistry books. Every time he comes to the lab, he takes a few books from the shelf to read.”

Yang Ping and Zaxi exchanged a glance. Zaxi's heart raced. There were books in the lab too?

Officer Yu realized what Professor Yang was planning to do and immediately stood up: "Take us to see him."

Li Xiong led them out of the conference room, through the corridor, and to Professor Zhou's former laboratory. The laboratory door was locked, but Li Xiong unlocked it with a key and went inside. The laboratory was much the same as when he last visited; the equipment was neatly arranged, and the work surface was clean. Against the wall was a metal bookshelf, neatly stacked with dozens of books.

Yang Ping walked to the bookshelf, but didn't touch it; he just stood there looking at it. Zaxi noticed that the spines of the books looked normal, without any obvious stains or damage. But Yang Ping's gaze was very focused, as if he were searching for something.

"Which of these books does Professor Zhou frequently read?" Yang Ping asked.

Li Xiong pointed to the second and third shelves of the bookshelf: "These are the main items. The top shelves contain textbooks and monographs, while the bottom shelves contain compilations of documents and conference proceedings."

Yang Ping squatted down and pulled a book from the second shelf. It was a thick, hardcover edition of "Organic Phosphorus Chemistry." He opened the cover and glanced at the title page, which bore Professor Zhou's signature and the date of purchase: 2005. He flipped through a few pages; the pages were clean, without any notes or creases.

He put the book back and pulled out another one. It was also a textbook on organic chemistry, and it was just as clean.

Yang Ping suddenly asked Zaxi a question that surprised him: "Li Xiong, in the past six months, has Professor Zhou asked you to buy anything for him? For example, organic solvents, reagents, or the like?"

Li Xiong thought for a moment and said, "Yes! About four or five months ago, he asked me to buy him a bottle of toluene. He said he needed toluene as a solvent for an experiment. I applied for it for him and got a bottle from the reagent warehouse. Later, he ran out of it and asked me to buy him another bottle."

Yang Ping asked, "What experiment does he need toluene for?"

Li Xiong shook his head: "He didn't say. He only said he needed it, so I bought it for him. He didn't let me ask about the specific experimental details, and I didn't ask any more questions."

Yang Ping then asked, "Where are those two bottles of toluene after they're used up?"

Li Xiong thought for a moment and said, "It should be in the drawer of his lab bench. He has a habit of keeping the empty bottles after he finishes using them, saying that they might be useful in the future."

Yang Ping walked to the lab bench and opened a drawer. Inside were several empty reagent bottles, all brown glass bottles of varying sizes. Yang Ping took them out one by one and placed them on the bench. Zaxi leaned over to look; the labels read: Toluene, analytical grade, 500ml, batch number… There were two bottles in total, both containing toluene.

Yang Ping picked up one of the bottles, unscrewed the cap, and smelled it. Then he handed the bottle to Zaxi: "Smell it."

Zaxi took the bottle and brought it close to the opening. A faint smell of organic solvents wafted out. He tightened the cap and looked at Yang Ping.

Yang Ping squatted down again and opened the second drawer. This drawer contained several old lab notebooks, their covers yellowed. He took one out and opened to the first page. It was Professor Zhou's handwriting, neat and tidy, with the date and experimental details written on it. Zaxi leaned closer to look and found that the contents were all records of organic synthesis experiments, detailing reaction conditions, feed amounts, and product processing in great detail.

Yang Ping flipped through the pages one by one. He stopped when he reached a point about six months ago.

The page read:

"Experimental objective: To synthesize a novel chiral organophosphorus ligand. References: Self-designed. Experimental procedures: Omitted (see attachment)."

Yang Ping frowned and turned the page. The next page was blank. He turned a few more pages, and they were still blank.

"What about the attachments?" he asked.

Li Xiong leaned over to take a look, then shook his head: "I don't know. Professor Zhou keeps his own lab notebooks. These notebooks were left in his drawer; I don't know what other attachments there are."

Yang Ping put the lab notebook back in the drawer and stood up. He walked to the bookshelf and glanced at the books again. Then he turned to Dr. Yuan and Officer Yu and said, "These books, and that bookshelf, all need to be tested for residues. Just like the books at home, they contain organophosphates, toluene, and xylene."

Dr. Yuan nodded: "I'll arrange for someone to do it right away."

It was already noon when they left the lab building. The sun was blazing, casting a blinding white light on the ground. Yang Ping stood under the sycamore tree in front of the building, silent for a long time. Zaxi stood beside him, not daring to speak.

After a while, Yang Ping suddenly said, "Zaxi, tell me your thoughts?"

Zaxi thought for a moment and said, "Those books in the lab are very suspicious. If someone tampered with those books, then Professor Zhou would also be exposed to toxins in the lab. Moreover, Li Xiong said that Professor Zhou asked him to buy two bottles of toluene in the last six months, and toluene happens to be a solvent for organophosphates."

Yang Ping nodded: "Anything else?"

Zaxi added, "The sentence written in the lab logbook is 'synthesize a novel chiral organophosphorus ligand.' If Professor Zhou has indeed synthesized a novel organophosphorus compound, it may not be within the scope of routine toxicology screening. This explains why the toxicology screening results are not yet available."

Yang Ping glanced at him, a hint of approval in his eyes: "Not bad, is there anything else?"

Zaxi thought for a moment and then said, "Chen Wei is Professor Zhou's student. He works on organophosphorus compounds and has a conflict with Professor Zhou. He has the motive and the ability."

"Officer Yu, what do you think?"

Yang Ping asked, "Ultimately, it's the police's expertise that solves the case."

Officer Yu thought for a moment: "We have the motive and the ability, all that's left is the evidence! But to be honest, we're most afraid of these kinds of cases because they're so technically demanding, but we're also the least afraid of them."

Zaxi, standing nearby, couldn't understand the officer's contradictory words.

Officer Yu smiled and said, "I'm afraid it's because once these kinds of cases involve things outside of our criminal investigation techniques, we become very passive. But at the same time, these kinds of cases themselves narrow down the range of perpetrators, because ordinary people can't use such high-tech methods."

Dr. Yuan said, "I think the most difficult thing now is not finding the suspect, but finding evidence that the suspect cannot deny. Right now, we have indirect clues: Chen Wei has a motive, and his company makes organophosphate products. But none of this can directly prove that he killed Professor Zhou. What we need is that bottle of organophosphate compound, or that solution smeared on the book, or physical evidence that directly connects him to this matter."

"Thank you, Professor Yang. It seems we need to study harder; the knowledge in our heads is simply not enough." Officer Yu shook Yang Ping's hand.

Yang Ping smiled and said, "We're just helping out with a small favor."

Officer Yu is a veteran criminal investigation team leader who has solved many cases. He took out a cigarette to light it, but suddenly realized it was inappropriate, so he immediately crumpled the cigarette into a ball and threw it into the trash can next to him.

"To be honest, I used to really dislike you bespectacled PhDs."

Officer Yu looked at Dr. Yuan.

"I always thought that you people only knew theory and had poor practical abilities. You were all show and no substance. Now I have to apologize to you, Dr. Yuan. If we hadn't focused on the slightest suspicious detail and consulted Professor Yang, we might have concluded that it was a case of sudden death. The organophosphates in that cup of tea weren't really a clue. It's not unusual for tea leaves to have a trace amount of organophosphates."