Chapter 304: Methods

2022-05-20

Even though I attended a science track in high school, it’s been years since then. Aside from a few common chemical names, most of these bottles are a mystery to me. I gently opened the bookshelf and found that I couldn’t smell anything inside—it must be tightly sealed.

Some jars are transparent, others are not. Looks like the materials were sorted based on their chemical properties. From what I see, these must be the substances the killer used to commit murder. Yet, after killing her victims, Deng Xuemei didn’t destroy these chemicals. That doesn’t sit right with me.

If she really intended to kill everyone and disappear, why leave these chemicals behind? Destroying them wouldn’t have been difficult, especially for someone like Deng Xuemei, who studies biology. Plus, from the leftovers in the kitchen and the shopping list in the bathroom, it doesn’t seem like she was planning this for a long time.

For someone said to be a ruthless killer, her daily life comes off as almost leisurely. If she was running away, why buy so many things just days before? It’s not like she’d take all this stuff with her. The food in the fridge, pajamas tossed on the bed—these all point to one thing: Deng Xuemei probably planned on coming back.

I frowned as Zhao Mingkun began taking each of the bottles out one by one.

Zhao Mingkun spoke up. “The killer used the chemicals in here to kill everyone, didn’t she? Maybe now we can piece together how they died. Right?”

I nodded. “Exactly. Given what we’ve seen, there are a few puzzles in the killer’s methods we need to crack. First, how did she get people to gouge their own eyes out without being there? And then, how exactly did Wang Yikai die, and which chemical was responsible?”

I tugged at my hair, speaking slowly. “Now we know that Yang Licheng and Wang Xin died because mercurous chloride broke down under sunlight, producing mercuric vapor. Wang Xin lit the incense burner, and the gas poisoned them both. So, the rest can probably be explained with science too.”

“And me?” I glanced at the many bottles Zhao Mingkun had arranged. “I think I’ve figured out the first part.”

“What do you mean?” Zhao Mingkun asked.

I pointed to my eyes. “Why did everyone gouge their own eyes out?”

That question had always haunted us. Zhao Mingkun looked genuinely surprised, then said, “Really? From what we saw, no one forced them to do it. That’s all I can imagine.”

I nodded. “It’s the same mechanism. The two strangest deaths were Liu Ruijie, who died locked inside his room, and Xing Yafang, who died in the elevator. Both were in completely closed spaces, alone.”

“Yeah,” Zhao Mingkun said, “but why?”

“Remember that time we ate at a street food stall?” I asked Zhao Mingkun.

He nodded. “Of course. That’s when you got chili in your eye.”

I snapped my fingers. “Exactly. When chili got in my eye, the pain was instant. I couldn’t help but rub it, wishing I could just dig my eyes out. If that pain were even sharper or deadly—what then?”

Now Zhao Mingkun caught on. “You mean something corrosive?”

I nodded. “Corrosive chemicals come in three main types: acids, bases, and others. If strong acids or bases get in someone’s eyes, the reaction is almost immediate.”

“And some of these chemicals could do just that,” I continued. “I’m not great with chemistry, but it stands to reason anything with ‘H’ at the start tends to be an acid, while things ending with ‘OH’ are bases. Deng Xuemei is a biotech student—her understanding of chemicals is way above ours.”

Zhao Mingkun rubbed his eyes. “So you’re saying Deng Xuemei sprayed something corrosive in their eyes, and the burning made them instinctively try to rub or remove it—but that only made things worse, until they clawed their own eyes out?”

I nodded. “That’s right. I checked the bodies—their eyes weren’t just gouged, some of the tissue was missing, probably eaten away by the chemical. It’s just like when you get chili in your eye—the more you rub, the worse it gets. They probably tried to rub it out, spreading the chemical deeper.”

I remembered that time at the noodle shop. “At least I could wait for the owner to toss me a wet towel to wipe my eyes, but in a life-or-death situation, you don’t get that luxury. They pulled their own eyes out just to stop the burning from spreading.”

Zhao Mingkun stayed silent, mulling it over.

I spoke again. “Hu Xiaoxue might’ve just been a test subject. Deng Xuemei could’ve wanted to see if this method worked. And what if she meant to kill Jiang Xiaochun, but accidentally killed Hu Xiaoxue instead?”

That thought made my skin crawl—if that’s true, then everyone else is in just as much danger.

Zhao Mingkun shook his head and studied one of the bottles. “That could explain the deaths, but how did the killer actually do it? For example, how did she spray the acid into someone’s eyes in the first place? That’s pretty strange.”

I leaned against the desk, still tugging at my hair. “The killer is a woman—that gives her an advantage. Take Liu Ruijie for example. Picture this: someone rings his doorbell. Liu Ruijie sees a woman outside—Deng Xuemei, though he doesn’t know her.”

I stroked my chin. “If it was a strange man at the door, anyone would be extra careful. But a woman, especially one who isn’t unattractive? Most guys would open the door.”

I closed my eyes and pictured the scene.

Liu Ruijie opens the door to a pretty woman. He doesn’t know why she’s there, but he lets her in. Women may seem vulnerable in some ways, but they’re strong in others. As Liu Ruijie considers what to say next—

Before he can speak, the woman—spray bottle in hand—hits him right in the eyes. Blinding pain erupts. Instantly, he knows he’s in serious trouble. His brain screams that if he doesn’t act fast, he might die right there.

Liu Ruijie slams the wooden door shut and locks it, his eyes barely able to open.

At that moment, he himself creates a locked-room scenario. Deng Xuemei, without hesitation, turns and leaves the hallway.

Panic sets in—he’s terrified the corrosive will go even deeper, damage his nerves. Wearing slippers, he stumbles, loses his footing, and falls hard to the ground. He never gets up again.

Maybe that’s what really happened.

I finished my theory. Zhao Mingkun said, “That’s definitely a possibility. But have you thought about this: if that’s how it happened, then what about Xing Yafang? Remember, we checked the surveillance footage. No one else appeared there at all. She was the only one in that hallway during those few minutes.”

Zhao Mingkun went on. “We saw the footage ourselves. Xing Yafang left, spent two minutes in the bathroom, then took the elevator—nothing happened during that stretch, and nobody came out of the bathroom afterward. This is the top floor—no one’s getting out a window. She was alone the whole time.”

He had a point. I frowned, deep in thought. So how did the killer pull it off? What sort of delayed trigger could do that?

I stared at the chemicals Zhao Mingkun had laid out on the desk. Suddenly, the answer hit me.

“I’ve got it!” I turned to Zhao Mingkun, excited. “Everyone who died—there’s something they all have in common. And that commonality is exactly why they died while alone!”

“A common factor?” Zhao Mingkun asked. “What is it?”