Controlled Experiment Chapter 3

Controlled Experiment – 3

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"Last month, my mom called me and said she saw a diamond ring she really liked at an auction abroad. It wasn't big, but it was exquisitely crafted and she loved it. You had to bid on a mould first before they placed the order for you, basically like putting down a deposit for a custom piece. Even after paying, it still took three or four weeks to make. But my mom didn't get it, another compatriot snatched it up. She's been full of resentment ever since and keeps calling me to complain."

Qin Yan cut him off with a dark expression. "If you're here to flaunt your wealth, give it a rest."

Du Yusheng leaned to one side and said, "The point I'm getting to is this, today, I saw that diamond ring on Mrs Luo's hand. According to Mrs Luo, she's been with Luo Daheng these past few days. But from auction to production to returning to the country, that ring would've taken at least a month. I just checked the calendar, Mrs Luo came back to the country only a couple of days ago, she couldn't have been with Luo Daheng at all."

"... What are you trying to say? It's easy enough to check travel records," Qin Yan said. "What's the point of Mrs Luo lying about something like that?"

"That's just it, she wants everyone to think their marriage is solid," Du Yusheng raised an eyebrow. "Why else would a wealthy woman go out of her way to convince me that she and Luo Daheng are head over heels in love? We're solving a case, not some nosy neighbours who care about these things."

Qin Yan caught on. He mentioned the housekeeper's name.

"Right," Du Yusheng snapped his fingers. "All the potted plants outside Luo Daheng's house use red soil from Yunnan, and the housekeeper probably just refreshed them this morning. The first time we saw him inside the house, his shoes were caked in red soil, filthy. But when we ran into him again outside, with Mrs Luo standing next to him, his shoes were clean. Why? Because I saw red soil powder from Yunnan on Mrs Luo's pinky when she wiped away tears. So Mrs Luo must have had some close contact with the housekeeper's shoes."

"... She polished them?" Xiao Bai looked incredulous. "Isn't this a bit too ambiguous..."

Du Yusheng struck a pose and pondered for a moment. "Well, she touched them somehow."

=========

On Wednesday afternoon, the usual weekly meeting was cancelled due to a murder case. Everyone in the team was sitting in the meeting room, staring blankly at one another. It was a rainy day, the kind best spent dozing under a duvet at home. Du Yusheng, who hadn't quite woken up even when he got up early, was still drowsy at the meeting. He yawned an uncountable number of times, his head tilted as he leaned against the marble slab behind him, looking half-paralysed, his dull eyes fixed on the screen ahead. Qin Yan sat next to him, his teeth grinding with irritation.

"Luo Daheng, male, fifty years old, a native of Huan Island City. Yesterday morning, his housekeeper noticed that the antihypertensive medicine placed by the door the previous day hadn't been taken, and later, he discovered that Luo Daheng had died in his study. Upon investigation, there was no sign of stolen property at the crime scene, no signs of struggle, and no trace of strangers entering or leaving. We also confirmed with the neighbours around the villa that they hadn't heard any shouting or unusual noises coming from the house that night," Xiao Bai switched to the next slide. "Three sets of footprints were found at the scene: one belonged to the housekeeper, who had visited the villa before Luo Daheng's death; another to his illegitimate son; and the third to the family doctor. This was also confirmed by reviewing the security footage from the camera at the entrance."

Du Yusheng yawned at the back and lazily jerked his chin toward Qin Yan.

"I'll go over what we found," Qin Yan stood up, holding the infrared remote and drawing circles on the screen. "Before his death, Luo Daheng suffered from hypertension, heart disease, and bronchial asthma. We found medication for all three conditions at the scene. Two bottles of salbutamol, one full and one empty. The bottle of nitroglycerin was empty, but I found traces of medication under Luo Daheng's tongue. However, it wasn't nitroglycerin, it was a common cold remedy."

"... The medicine was swapped," Xiao Bai frowned as he scribbled in his notebook. "So he died because he didn't get the proper medication in time?"

"That's the issue," Qin Yan pointed toward Du Yusheng. "Just as Du Yusheng suspected, Luo Daheng didn't die from missing his medication, he died from an overdose of nitroglycerin."

Du Yusheng squinted and grinned at Qin Yan, drawing a circle around his mouth with his finger, smug as anything.

Before his death, Luo Daheng's lips had turned bluish-purple. This was methemoglobinemia, a condition most commonly caused, apart from heredity, by nitroglycerin overdose. It leads to oxygen deprivation in red blood cells, which in turn causes the mucous membranes and skin to take on a purplish hue.

Xiao Bai was clearly a bit slow on the uptake. "I always thought nitroglycerin saved lives, I never knew it could kill. So it really was murder?"

"That's not all," Qin Yan switched to a new slide. "We also found something else in Luo Daheng's stomach."

A crumpled white piece of paper was sealed inside a transparent plastic bag. It was very small, no bigger than a fingernail. The paper had been neatly folded into a square, and thanks to the protection of the plastic bag, it had sustained no damage whatsoever. Qin Yan glanced in Du Yusheng's direction before switching to the next slide. The folded paper inside the bag had been opened, and there was black text on white paper. In bold, printed Songti font were two large words: Controlled Experiment.

Du Yusheng abruptly stood up, took a few steps forward and stared at the image, his mind buzzing. The letters in the image, Songti font, printed, offered nothing that could be traced through handwriting. Just twenty upright letters, printed left to right on a square sheet of paper. Du Yusheng suddenly felt wide awake, more alert than he would've been with a cup of coffee.

"Are there any fingerprints on the paper?"

Qin Yan shook his head. "Apart from those two words, there's absolutely nothing useful on that note."

Judging both from the cause of Luo Daheng's death and the paper itself, it was clear Luo Daheng had been murdered. This was no natural death, contrary to earlier assumptions. Du Yusheng stood by the window, staring at the two words, and let out a deep sigh. Something unnameable surfaced in his eyes. From a distance, Xiao Bai watched, unable to read him at all.

=========

Since the meeting ended, Du Yusheng had stayed holed up in his office without coming out. The blinds were down and Xiao Bai couldn't see a thing from the outside. Several hours had passed, he hadn't even gone to the washroom, and Xiao Bai was genuinely starting to worry about his bladder.

Just before one o'clock, Qin Yan came looking for Du Yusheng. As he reached the door, Xiao Bai stopped him.

Pulling him aside, he whispered, "Brother Qin, Brother Yu hasn't come out all afternoon. This case... it's a real headache, isn't it?"

Qin Yan chuckled. "Your Brother Yu never wastes brainpower on these things."

Xiao Bai didn't buy it. Qin Yan took him into Du Yusheng's office with him without so much as knocking.

Du Yusheng was the same as ever, staring at his computer screen in deep concentration, still as a statue, his fingers resting on the mouse. Qin Yan glanced down; Du Yusheng's throat bobbed up and down in sync with the movement of the mouse. Qin Yan had been close friends with Du Yusheng for many years. Sometimes, Qin Yan considered himself a straight man, but when he saw Du Yusheng that focused, he wasn't so sure. Then Qin Yan'd get home after work and feel straight again. It had been back and forth like this for years, to the point that even Qin Yan himself couldn't say for certain any more.

There were still three dried-up cups left on the desk. Qin Yan rolled up his sleeves and, quite naturally, tossed them into the nearby sink, deftly turning on the tap.

"Here to give me the autopsy report?"

The sound of running water was loud, nearly drowning out Qin Yan's voice, and his reply was muffled: "It's with Xiao Bai." Then he turned to Xiao Bai and said, "Xiao Bai, show him."

Du Yusheng took it, flipped through a couple of pages, then set it aside and turned his attention back to the computer screen.

Xiao Bai blinked rapidly, restless in his seat, and asked, "Brother Yu, what exactly is a controlled experiment?"

Du Yusheng was busy with what he was working on and couldn't be bothered to pay attention, brushing him off with, "It's like you taking a flashlight and shining it on an experiment in the dark."

"......"

Qin Yan couldn't bear to watch any more and picked up the explanation. "Generally, when conducting an experiment to demonstrate the effect or significance of a certain factor on a subject, all other variables are kept constant apart from the one being tested, and the outcomes are compared. That's a controlled experiment."

Xiao Bai said nothing in response.

Du Yusheng rolled his eyes. "Make it simpler, he didn't get that."

Qin Yan neatly put the washed cups back in Du Yusheng's cupboard where they belonged.

"Let me give you an example: suppose you wanted to experiment on Du Yusheng. You'd need to find a model exactly like him in appearance, height, weight, and every other condition. Then you'd change just one of those factors in one of them to achieve your experimental aim..."

The second half of Qin Yan's sentence grew quieter, and he glanced over at Du Yusheng, his thoughts drifting to something else.

That anonymous email.

Twins.

If humans were to be considered as experimental subjects, then twins would undoubtedly be the ideal model for a controlled experiment.

But the person in question, Du Yusheng, seemed entirely unaware. His mouth was stuffed full of cherries left over from last time, though whether they'd expired or not was anyone's guess.

Xiao Bai leaned over to glance at his computer. "Brother Yu... so you've spent the whole afternoon just busy with this?"

On the screen was a frontal photo of Du Yusheng. Last month, he cracked a high-profile case. The bureau commended their team and wrote a special article that was circulated throughout the department as praise. Du Yusheng's photo had been placed alongside others, it was a group photo.

Du Yusheng clicked the mouse and frowned. "Next time, tell the publicity department to make my photo bigger. This, I've had to edit it myself. Wasted a whole afternoon, haven't even gone to the washroom."

Xiao Bai watched as Du Yusheng set that image as his desktop wallpaper, unsure what sort of expression he should be making in response.

"Oh right, what's the update from the housekeeper's side?" Du Yusheng shut his laptop.

Xiao Bai replied, "Someone's gone over there, we should have news soon."

Du Yusheng nodded and opened the autopsy report that Qin Yan had brought back.

With a slight tilt of his chin, Qin Yan asked, "Any thoughts?"

Du Yusheng raised a single finger. "I've been thinking about how that nitroglycerin ended up inside Luo Daheng. I made time this afternoon to rewatch the surveillance a few times. The last person to see Luo Daheng alive was his private doctor, the doctor left the villa at half past ten, and Luo Daheng's time of death was in the early hours of the morning. In other words, if one of them had fed Luo Daheng the drug, Luo Daheng wouldn't have died so much later. So I think there's only one answer."

Du Yusheng paused, fingers tapping lightly on the desk, "Luo Daheng took the nitroglycerin himself."

Xiao Bai rubbed his chin. "He poisoned himself? Then this counts as suicide."

Du Yusheng didn't bother answering Xiao Bai's idiotic remark and instead looked toward Qin Yan.

"Qin Yan, what kind of person would use a controlled experiment?"

Qin Yan glanced upwards, thinking for a moment. "Plenty of people use them, but those who use them regularly... are biology fields, mostly. And people like me, medical fields. I did some back in school."

They were thinking along the same lines. Du Yusheng pulled a photograph out of the drawer and slid it over to the two of them.

The man in the photo was strikingly handsome, with a faint smile on his face. He wore a white lab coat, and the overall impression he gave was one of cleanliness and decency.

Qin Yan lowered his gaze to the bottom of the photo, where the man's name was written.

Li Yao.

Luo Daheng's private doctor.

‿︵‿︵ʚ˚̣̣̣͙ɞ・❉・ ʚ˚̣̣̣͙ɞ‿︵‿︵

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Translator Notes

Please feel free to comment any mistakes I made so I can improve and do better as I go through the book.

Translated: May 12, 2025 by Angel

Edited: May 28, 2025 by Angel