Another Method

"Mr. Lin, can you find bloodstains that have been washed away?"

Suzuki Sonoko asked impatiently.

Without realizing it, this young lady who had come to "meet her idol" had placed herself in the role of an investigator, focusing all her attention on the case.

She had never experienced this sense of involvement before.

That was because Lin Xinyi solved cases through knowledge, not through extraordinary intelligence like those famous detectives.

Intelligence was a gift from heaven, but knowledge was something ordinary people could acquire.

So at this moment, even an ordinary person like Suzuki Sonoko felt a sense of participation—of "I understand" and "I get it too."

Rather than the alienation and confusion she used to feel while watching Kudo Shinichi solve cases: "What did you understand?" and "You figured it out again?"

"Wouldn't blood just get washed away by water?"

Like an eager student, Suzuki Sonoko added her question.

"It only looks clean on the surface."

"After blood is washed away, trace amounts that are hard to notice still remain. Scientific methods, such as the Luminol reaction, can reveal them."

Lin Xinyi explained:

Luminol, also known as Luminol Reagent, emitted blue light when oxidized.

The hemoglobin in blood could catalyze a reaction between luminol and hydrogen peroxide, producing a blue-green fluorescence.

This detection method was extremely sensitive. It could detect even tiny traces of blood diluted to one part in a million.

So it was basically impossible to evade Luminol detection simply by washing with water.

If someone truly wanted to erase the evidence, they would first need to use strong oxidizers such as hydrogen peroxide to destroy human DNA, then rinse the scene with animal blood to conceal it, and finally wash it again with bleach.

But that murderer had fled the scene in a hurry and then been trapped on the platform. He definitely had not had the conditions to clean up the evidence so thoroughly.

"Luminol..."

Kudo Shinichi, standing nearby, finally reacted:

"Right, there really is something like that."

"But I don't think I've ever seen the Tokyo Metropolitan Police Department use it."

He suddenly remembered that he had learned about this in Hawaii as well.

But after solving so many cases, whether it was him, other detectives, or especially the police, practically no one had ever used this kind of forensic technique.

Without anyone noticing, everyone had nearly forgotten about it.

"Huh? You've never seen the Tokyo Metropolitan Police Department use it?"

Lin Xinyi felt his scalp tingle.

Luminol had already been used for blood detection in criminal investigations since the 1930s. Surely the Tokyo Metropolitan Police Department had not failed to equip themselves with it even now?

No—considering the level the police in this world had displayed, perhaps they had it but simply never thought to use it.

Otherwise, if they actually used all the Criminal Science and Technology methods the police should have had, what would detectives even be needed for?

I just hope the Tokyo Metropolitan Police Department is reliable this time.

At the very least, they should have the most basic investigative equipment.

Lin Xinyi sighed helplessly to himself.

Then, having decided to test for blood with the Luminol reaction, he left the crime scene with Kudo and Sonoko and came out onto the platform.

Only then did Lin Xinyi realize—

The true difficulty of the investigation did not lie in technical equipment, but in the people: the more than one hundred people who had been forcibly kept behind to cooperate with the investigation.

The moment Lin Xinyi and the other two emerged from the restroom, the waiting passengers being held on the platform immediately looked over.

"They're out! They're out!"

"Have you figured out who the murderer is?"

More than a hundred pairs of eyes turned toward them in unison, most of them filled with impatience.

"Uh... not yet."

"But we've found a way to identify the murderer. Once the Tokyo Metropolitan Police Department's technicians arrive, we'll be able to screen everyone and determine who it is."

Kudo Shinichi stepped forward to speak. He was more famous and held greater authority in front of the public.

But this time, even the famous detective's reputation was useless.

"What? We have to wait for the Tokyo Metropolitan Police Department?"

"Does that mean Kudo Shinichi hasn't found the murderer at all?"

Everyone was deeply disappointed, and the reputation of the famous detective Kudo Shinichi suffered once again.

In these passengers' imaginations, with the "Heisei Holmes" present, the murderer should have been found within minutes.

That was why they had patiently waited until now, believing the case would be solved quickly.

But now, this Savior of the Japanese Police was saying that he had not found the murderer and that they still had to wait for the Japanese police to arrive before screening could even begin.

What a joke. Even the savior could not find the culprit—could the one being saved possibly do any better?

"Can those freeloaders really find the murderer?"

"Once those useless cops get here and start slowly screening for the murderer, how much more time will that waste?"

"And if they still can't find them, are they going to keep all hundred-plus of us detained?"

The waiting passengers began shouting noisily.

When it had nothing to do with them, they preferred to stay out of it. Besides, life moved fast for city residents, and they had no desire to waste too much time over the death of someone they did not know.

Whether the murderer was caught had nothing to do with them. But if this delayed their afternoon work and got them written up by their companies, that would be a truly unacceptable disaster.

"Hey, hey..."

The passengers' tone grew heated again.

"Just tell us—when is this going to be over?"

Kudo Shinichi had no answer. He could only turn to Lin Xinyi with a pleading look.

Lin Xinyi stepped forward and tried to speak calmly.

"One afternoon. It should be resolved within one afternoon."

Luminol Reagent was actually a mixture of luminol and hydrogen peroxide, and it had to be mixed on site in the proper proportions before use.

The light produced by the Luminol reaction was extremely faint and generally lasted only a few seconds, making it difficult to observe with the naked eye. Curtains also had to be set up to block outside light and create a dark room before it could be used.

Even with all those preparations complete, screening more than a hundred people one by one within an afternoon was already a conservative estimate.

But once he said that, the passengers became even more unsettled.

"One afternoon? We have to be delayed for that long?"

"Hey, hey, I don't want to wait anymore! I'm not the murderer, so let me leave!"

Some people had already begun making an impatient fuss.

"Yeah! With a famous detective here, we thought it would be resolved in minutes."

"But now we have to wait for the Tokyo Metropolitan Police Department, and it's turned into an entire afternoon—can it really be solved in one afternoon? Won't you keep detaining us afterward?"

More and more people joined in, and the atmosphere became increasingly tense.

Judging by their posture, they were ready to force their way out.

"Mr. Kudo, Mr. Lin."

At that moment, a station employee responsible for maintaining order approached with an ugly expression.

"Why don't we just forget it? There are too many people. We really can't stop them."

"If they lose control and a conflict breaks out, we can't bear that responsibility."

"This..." Both Kudo and Lin Xinyi were helpless.

Indeed, more than a hundred people making a scene was no small matter.

No organization wanted to take responsibility for provoking a mass conflict.

Forget the station staff—even if the Tokyo Metropolitan Police Department stepped in, they would have to obediently let them go in a situation like this.

And although Ran's fighting ability was highly intimidating, everyone knew that this young girl could not possibly truly hurt anyone.

"Why not just let them go?"

"If this continues, something really might happen."

The employee pleaded again. He clearly wanted to get rid of this hot potato as soon as possible.

Just like that, the passengers wanted their freedom back, the employees wanted to avoid risk, and only Lin Xinyi, Kudo, Ran, Sonoko, and the other few still cared about the victim.

The situation was on the verge of spiraling out of control.

Some people had already started walking away by force, while the station employees responsible for maintaining order did not dare stop them at all.

"Wait!"

At the critical moment, Lin Xinyi stepped forward.

"Everyone, don't rush to leave."

"Give me ten minutes. I'll definitely find the murderer within ten minutes!"

"Huh?"

The enraged passengers immediately fell silent.

"You can solve it in ten minutes? You're not lying to us, are you?"

"Trust me." Lin Xinyi spoke with utmost solemnity. "As long as you cooperate honestly with my investigation, ten minutes will be more than enough."

"And what if you still haven't found them by then?" someone in the crowd asked provocatively.

"...Sigh." Lin Xinyi let out a soft sigh and promised helplessly, "Then we'll let everyone go!"

"This..."

The hundred-odd passengers fell silent for a while before finally accepting the condition.

"Fine. Then we'll wait here for another ten minutes."

The platform finally quieted down.

Suzuki Sonoko immediately hurried over and asked worriedly.

"Mr. Lin, ten minutes is only enough time for the Tokyo Metropolitan Police Department's people to reach the scene. How could there possibly be time for that Lumina—Luminol test?"

"Or, if it really comes down to it..."

"I can help you stop them."

Suzuki Sonoko thought Lin Xinyi had been forced into using a delaying tactic.

So, to find the murderer and ease her idol's burden, Miss Suzuki was prepared to stop keeping a low profile and personally help hold back those unwilling to cooperate—

Back then, Jack Ma had made tens of millions of internet users willingly call him Dad. Now, Miss Suzuki, who also possessed the power of money, naturally had plenty of ways to make the hundred-plus people present today behave obediently.

At most, she would just have to throw more money at the problem. Money was what she lacked least.

But Lin Xinyi refused Suzuki Sonoko's offer. "It's fine. I can handle it."

"Mr. Lin, I really can help."

"Actually, I'm from the Suzuki finan—"

Sonoko instinctively assumed that Lin Xinyi did not know her identity and thought she could not help, which was why he had politely turned her down.

But just as she was about to reveal who she was and dazzle Lin Xinyi, he spoke to her very seriously.

"Don't worry. I really do have another way to find bloodstains."

"This method isn't as accurate as Luminol, but under the current circumstances, it's the most suitable one."

"Oh?" The worry in Suzuki Sonoko's eyes turned into curiosity and admiration. "There's another method? How does it work?"

"Haha."

Lin Xinyi looked up at the ceiling and made a meaningful joke.

"This underground platform is too cold and damp. It's easy for filth to hide here."

"So let's go aboveground and let everyone see the sun."