Another Method

"Mr. Lin Xinyi, you can find bloodstains that have been cleaned?"

Suzuki Sonoko asked, her voice eager.

Unbeknownst to herself, this young lady, who had come to "fangirl," had fully immersed herself in the role of an investigator, her attention completely focused on the case.

This sense of involvement was something she had never experienced before.

This was because Lin Xinyi solved cases using knowledge, unlike those Famous Detectives who relied on their extraordinary intellect.

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

So, at this moment, even as an ordinary person, Suzuki Sonoko felt a sense of "I understand," "I get it" – a feeling of participation –

Rather than the usual disconnect and confusion she felt when watching Kudo Shinichi solve cases, thinking, "Understand what?" or "You get what now?"

"Won't blood be washed away by water??"

Like an eager student, Suzuki Sonoko added.

"Only on the surface."

"Even after being washed, there will still be trace amounts of blood that are difficult to detect. Through scientific methods, such as the Luminol reaction, we can find them."

Lin Xinyi explained:

Luminol, also known as Luminol, emits a blue light when it oxidizes.

The heme in blood can catalyze the reaction between Luminol and hydrogen peroxide, producing a blue-green fluorescence.

This detection method is extremely sensitive, capable of detecting even trace amounts of blood diluted to one part per million.

Therefore, it's virtually impossible to evade Luminol detection by simply washing with water.

To truly clean up traces, one would first need to destroy the human DNA with strong oxidizers like hydrogen peroxide, then wash the scene with animal blood to cover it up, and finally, rinse it again with bleach.

But the culprit fled the scene in a hurry and was then trapped on the platform; he absolutely had no means to clean up the traces so thoroughly.

"Luminol, huh?"

Kudo Shinichi on the side reacted belatedly:

"Right, there is such a thing."

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

He suddenly remembered that he had learned this very fact in Hawaii.

However, despite so many cases being solved, neither he nor other Detectives, let alone the police, had ever really used this technical method.

Unconsciously, this thing was almost forgotten by everyone.

"Huh? Never seen the Tokyo Metropolitan Police Department use it?"

Lin Xinyi's scalp tingled when he heard that:

Luminol had been used in forensic blood testing since the 1930s. Surely the Tokyo Metropolitan Police Department wasn't still unequipped with it?

Given the level of performance displayed by the Tokyo Metropolitan Police Department in this world, it was also possible they had it but just didn't think to use it.

Otherwise, if they utilized all the forensic science techniques available to the police, there wouldn't be any need for Detectives.

"I hope the Tokyo Metropolitan Police Department will be more reliable this time."

"At least they should have the most basic investigative tools."

Lin Xinyi sighed helplessly in his heart.

Then, having decided to use the Luminol reaction for blood testing, he, Kudo, and Sonoko left the crime scene and went to the platform outside.

It was then that Lin Xinyi realized:

The real difficulty in investigating wasn't the technical equipment, but the people—the over a hundred individuals who had been forcibly detained to cooperate with the investigation.

As soon as Lin Xinyi and the other two emerged from the restroom, the waiting passengers, who were being held on the platform and not allowed to leave, immediately looked over:

"They're out, they're out!"

"Did you find out who the killer is?"

Over a hundred pairs of eyes stared in unison, mostly filled with impatience.

"Uh, not yet."

"But we've found a way to identify the killer. Once the Tokyo Metropolitan Police Department's technical personnel arrive, we'll be able to pinpoint who the killer is."

It was Kudo Shinichi who stepped forward to speak; he had a higher profile and more authority with the public.

But this time, even the great Detective's authority was ineffective:

"What? Wait for the Tokyo Metropolitan Police Department to arrive?"

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

Everyone was greatly disappointed, and Famous Detective Kudo Shinichi's reputation suffered again.

In the imagination of these passengers, with "Heisei Holmes" present, it should only take a few minutes to find the killer.

So, thinking the case would be solved quickly, they patiently waited until now.

But now, the Savior of the Japanese Police said he hadn't found the culprit and they'd have to wait for the Tokyo Metropolitan Police Department to arrive before they could start the search.

Are you kidding me? If the Savior couldn't find them, how would those who were "saved" have a chance?

"Can those freeloaders really find the killer?"

"Waiting for those useless police to come and slowly search for the culprit—how much more time will that waste?"

"If they still can't find them, are they going to keep over 100 of us detained indefinitely?"

The waiting passengers began to clamor noisily.

It's easy to ignore problems that don't concern you, and the pace of life in a big city is generally fast-paced. They weren't willing to waste too much time just because of a dead person they didn't know.

Whether the killer was caught or not had nothing to do with them, but if this incident delayed their afternoon work and they received a disciplinary warning from their company, that would be a truly unacceptable major issue.

"Hey, hey!"

The passengers' tone grew heated again:

"Just tell us, when will this be over?"

Kudo Shinichi was speechless and could only look to Lin Xinyi for help.

Lin Xinyi stepped forward and tried to speak in a calm tone:

"One afternoon, it should be resolved in one afternoon."

Luminol reagent is actually a mixture of Luminol and hydrogen peroxide, and it needs to be prepared on-site in the correct proportions before use.

Furthermore, the light emitted by the Luminol reaction is extremely faint, usually lasting only a few seconds, making it difficult to observe with the naked eye. Curtains need to be set up to block out light, and a darkroom must be prepared before it can be used.

After all these preparations, and then individually searching over 100 people, one afternoon was still a conservative estimate.

But as soon as he said this, the passengers became even more agitated:

"One afternoon? It's going to take that long?"

"Hey, hey, I don't want to wait anymore! I'm not the killer anyway, just let me go!"

Some people were already starting to get impatient and cause a commotion.

"Yeah! With the Famous Detective here before, we thought it would be solved in minutes."

"Now we have to wait for the Tokyo Metropolitan Police Department to arrive, and it's turned into a whole afternoon—can it really be solved in one afternoon? They won't keep us detained even longer, will they?"

More and more people echoed these sentiments, and the atmosphere on site became tense.

Judging by their demeanor, they looked ready to force their way out.

"Mr. Kudo, Mr. Lin."

At this moment, the train station staff responsible for maintaining order approached with a grim expression:

"How about we just let them go? We really can't stop this many people."

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

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

Indeed, over 100 people causing a commotion was no small matter.

No organization wanted to bear the responsibility of inciting mass conflict.

Not to mention the train station staff, even if the Tokyo Metropolitan Police Department stepped in, they'd have to let them go in this situation.

And while Ran's fighting prowess was intimidating, everyone knew this young girl couldn't actually hurt anyone.

"Should we just let them go?"

"Something's really going to happen if this continues."

The staff member asked again; he clearly wanted to quickly get rid of this hot potato.

And so, the passengers wanted their freedom, the staff wanted to avoid risk, and only Lin Xinyi, Kudo, Ran, and Sonoko—a mere four people—were still considering the deceased.

The situation was clearly about to spiral out of control.

Some people had already started to forcefully walk away, and the train station staff responsible for maintaining order didn't dare to stop them at all.

"Wait!"

At this critical moment, Lin Xinyi stepped forward.

"Everyone, don't rush off yet."

"Give me 10 minutes. I will definitely find the killer within 10 minutes!"

"Huh?"

The agitated passengers immediately quieted down:

"You can solve it in 10 minutes? You're not lying, are you?"

"Trust me." Lin Xinyi said with utmost seriousness, "As long as you cooperate honestly with my investigation, 10 minutes is completely enough."

"What if you still haven't found them by then?" another troublemaker in the crowd asked.

"Sigh." Lin Xinyi let out a soft sigh and reluctantly promised, "Fine, we'll let them go!"

"But..."

The more than 100 passengers fell silent for a moment, then finally agreed to the condition:

"Alright, we'll wait here for another 10 minutes."

The platform finally became quiet.

Suzuki Sonoko, meanwhile, eagerly leaned in and asked with some concern:

"Mr. Lin Xinyi, 10 minutes is barely enough time for the Tokyo Metropolitan Police Department to arrive. How will there be enough time for that Luminol test?"

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

"I can help you stop them."

Suzuki Sonoko thought Lin Xinyi was just using a delaying tactic out of desperation.

So, to find the culprit and to help ease her idol's worries, Miss Suzuki was ready to stop being low-key and actively help keep these uncooperative people there—

Back then, Jack Ma could make millions of netizens willingly call him "Dad." Now, Miss Suzuki, who also possessed the power of money, naturally had ways to make the more than 100 people present today obedient.

It was nothing more than spending a bit more money; the one thing she wasn't short of was money.

But Lin Xinyi rejected Suzuki Sonoko's kind offer: "It's alright, I can handle it."

"Mr. Lin, I really can help."

"Actually, I'm the Suzuki Fina..."

Sonoko instinctively thought that Lin Xinyi simply didn't know her identity and felt she couldn't help, which was why he politely declined her.

Just as she was about to reveal her identity and 'blind' Lin Xinyi with it, Lin Xinyi very seriously told her:

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

"Although this method isn't as accurate as Luminol, in this situation, it's the most suitable."

"Oh?" The concern in Suzuki Sonoko's eyes turned into curiosity and admiration: "There's another way? How do you do it?"

"Haha."

Lin Xinyi looked up at the ceiling and joked meaningfully:

"This underground platform is too damp and cold; it's easy for dirt and grime to hide."

"So, let's go above ground, and let everyone see the sun."