Chapter 22

Chapter 22 2. Eden Lake-13

Liu Yi suddenly received a steel palm strike from An Pingdong, stumbling a small step forward. Taking advantage of the dark room where no one could clearly see his face, he made a childish pout, his tone revealing a hint of reluctance: “Mm, it’s not really my credit—it was the evidence department that found it…”

That day, he had sent the drowning water samples extracted from Su Ruirui’s stomach and duodenum to the evidence department for chemical analysis. Unexpectedly, they found fatty alcohol polyoxyethylene ether at concentrations far exceeding normal tap water.

Fatty alcohol polyoxyethylene ether is a common industrial surfactant, often used in detergents. It is unaffected by water hardness and stable in acidic, alkaline, or saline environments, so it can remain intact even in the strong acid environment of gastric juice.

After finding this, they collected all possible water samples from the school and eventually detected the same epoxy value fatty alcohol polyoxyethylene ether in the toilet tank of the girls’ dormitory bathroom. Verification confirmed it came from toilet tank cleaner.

Once it was established that Su Ruirui drowned not in the school’s artificial lake but in the dormitory toilet, the police quickly obtained a search warrant.

After finding nothing unusual in Su Ruirui’s own dorm, they searched the dorm of class monitor Lin Yuan, who had invited her to a party the night before her death—there, they indeed found pools of blood on the bathroom floor.

“Eh, anyway, it’s all thanks to your institute, haha!”

An Pingdong had only a vague idea of forensic sub-specialties. For detectives like them, as long as the forensic team provided accurate conclusions, everything was fine.

And it was Liu Yi who proposed that Su Ruirui didn’t drown in the artificial lake and noted the contradictory surveillance footage.

With just these two points, An Pingdong had to admit that this young overseas-trained forensic scientist, who was already head of a department and third in command, truly had skill.

“By the way, how is your case progressing now?”

Liu Yi watched Jiang Xiaoyuan diligently photograph and sample each bloodstain, label them, and put them into the evidence box, then asked the two officers standing nearby.

Three days had passed since Qi Shanyu last came to the institute. Since they had confirmed the water source where Su Ruirui drowned, the police inquiry and evidence collection should have made some progress.

“Oh, about that.”

An Pingdong replied, “Su Ruirui’s roommate Shen Junting admitted that the person seen in the library entrance surveillance video was actually her in disguise.”

He opened his phone album and showed the photos to Liu Yi.

“Su Ruirui is 1.55 meters tall, Shen Junting 1.57 meters, only a two-centimeter difference. Both are slim. Wearing the uniform skirt in the dark, with the camera at a skewed angle from the library, you can’t see the face clearly. Based on hairstyle and clothing alone, it’s very hard to tell them apart.”

An Pingdong shrugged.

“Since the body in the water was Su Ruirui’s, seeing someone jump in with similar height, build, and hairstyle, we naturally assumed it was Su Ruirui herself.”

“The last time you questioned Shen Junting, I remember she had two braids.”

Liu Yi looked at the photo of the young girl with her head down, looking haggard. After the braids were undone, her hair length and jawline were indeed similar to the deceased Su Ruirui. The library camera was far and angled, with low resolution; if it weren’t for the diatom test raising the possibility of a ‘substitute,’ the surveillance footage alone wouldn’t reveal a flaw.

“Yes, she said Lin Yuan taught her. Braids are very different from Su Ruirui’s loose hair, making it hard for the police to link their appearances.”

An Pingdong ran a finger along his thick lower lip.

“Shen Junting said that Lin Yuan, unhappy with the snacks Su Ruirui bought, pushed her to the ground and beat her. Su Ruirui’s face hit the washbasin, causing a nosebleed. Lin Yuan and her roommate then pressed her head into the toilet and flushed. For some reason—maybe a clogged toilet—water accumulated, and by the time they noticed she stopped struggling, she was dead.”

Liu Yi frowned, imagining the scene.

“If Lin Yuan and her roommate did it, why didn’t Shen Junting call the police, and instead act as the ‘lake-jumping substitute’?”

“According to Shen Junting, she had previously been pressured by Lin Yuan and friends and also bullied Su Ruirui. She probably feared being implicated if the truth came out.”

An Pingdong recalled the interrogation record:

“Moreover, Lin Yuan threatened her: if she didn’t comply, she’d be bullied to death next. It would be her turn.”

He sighed. “I never expected a high school girl could plan a cover-up so thoroughly! After drowning a classmate, she thought to throw the body in the school lake and use a student of similar build to film a fake suicide video.”

“Officer An, don’t underestimate today’s youth.”

Liu Yi chuckled softly, “A child calm enough to think of damage control after killing—one could say she has great potential.”

“Also…”

Qi Shanyu frowned, thinking of Su Ruirui’s nearly cremated body. “Her plan almost succeeded.”

“Did Lin Yuan admit to the murder?” Liu Yi asked.

“No.” An Pingdong shook his head.

“The girl has strong mental fortitude. She only admitted that they drank a little and got out of hand. Su Ruirui slipped in the dorm bathroom and hurt her nose. Everything else, she denies.”

“Too many crime shows nowadays. Everyone knows about Luminol, teaching clever young people to cover tracks.”

Liu Yi sneered, “Knowing the substitute plan was exposed, and that even cleaned bloodstains fluoresce, she already prepared an explanation.”

An Pingdong shrugged.

For a suspect’s denial, he wasn’t too anxious: “She’s just a teenage girl. More questioning will reveal cracks.”

“Mm…”

Liu Yi didn’t reply immediately, his eyes fixed on the fluorescent blue blood in the dark bathroom, deep in thought.

“I have a question…”

He paused, then said, “When Su Ruirui’s body was found, her shirt and skirt were clean.”

“You mean, no bloodstains?”

Qi Shanyu realized quickly. “Indeed, seeing all the blood on the floor, it’s hard to imagine that her nosebleed didn’t stain her clothes at all.”

“Right.”

Liu Yi nodded, a faint smile in the dark, clearly impressed with Qi Shanyu’s insight.

“Blood on clothing, even soaked in lake water overnight, would leave traces detectable with fluorescent reagents. But I’m certain, at the time, Su Ruirui’s clothes showed no blood.”

“Did Lin Yuan and the others change her bloodied clothes?”

An Pingdong clapped, eyes gleaming with excitement. “If we find the clothes, we can almost force Lin Yuan to confess!”

Qi Shanyu shook his head slowly. Many days had passed. He didn’t think the girl who thought to use a substitute would forget to handle the bloodied clothes.

“Mm, one more point.”

Liu Yi continued:

“The artificial lake is not far from the dorm, but still a five-minute walk. The dorm is on the fifth floor with no elevator. Even if Su Ruirui is small and light, the suspects were several young girls. Whether carrying or dragging, moving the body downstairs and to the lake would be very difficult. So, how did they transport it?”

He looked at An Pingdong and Qi Shanyu. “You must have asked Shen Junting this, right?”

“Of course we asked.”

An Pingdong shrugged.

“But she told us she only pretended to be Su Ruirui at the lake to record the video. She climbed the railing, jumped down, carefully walked along the platform below, then climbed back to the shore and returned to her dorm.”

He paused, adding, “She insists she never participated in handling Su Ruirui’s body, so she doesn’t know how Lin Yuan moved it to the lake.”

“…”

Liu Yi thought for a moment and said lightly, “If it were me, when unable to carry it, I’d probably use something with wheels…”

He spoke slowly, word by word: “Like a suitcase.”

Liu Yi looked up, a faint smile in the dim room.

For some reason, though faint, it sent a chill down Qi Shanyu’s spine.

“Anyway, Su Ruirui is small. Curling her up in a slightly larger box shouldn’t be a problem, right?”

“!!”

An Pingdong’s eyes lit up like he’d been injected with adrenaline. “A suitcase that size is much harder to handle than a school uniform! And in a boarding school, you can’t just toss it outside easily!”

He grabbed Liu Yi’s shoulder firmly. “If we find the suitcase, can you confirm it contained a body?”

“Of course.”

Liu Yi raised an eyebrow, chuckling softly.

“Every contact leaves a trace. That’s a classic in forensic textbooks.”