The killer finally surfaced.

Dressed in a typical short-sleeved shirt, denim trousers, and a slightly old but cleaned shoulder bag around his waist, the man looked less like a murderer and more like a young office worker passing by.

No one in the crowd would notice him so ordinary.

But at this moment, this man is like salt melted in water, precipitated by the righteous sun.

More than a hundred pairs of eyes were locked on his body in unison, so that he could no longer hide.

"I...."

The young man, who was regarded as the murderer by Lin Xinyi, had a stiff face.

But in the end, he responded:

"What are you kidding?!"

"Because a few flies say I'm a murderer? I just ate ice cream a while ago and got frosting on my hands from the ice cream, and that's normal, right? ”

The young man defended himself with such excitement.

"Huh." Lin Xinyi gave him a disdainful smile back.

Indeed, the trick of flying flies to find blood is actually very limited and very easy to interfere with.

Things like frosting, cream, honey and the like that are common in life can also completely attract flies. The presence of flies does not mean that there must be blood on the person.

It is not the same now as it was in ancient times.

In ancient times, flies could be relied on to find blood to make the murderer bow his head and confess, it should be because...

If he did not admit his guilt, the murderer would probably be brought back to the yamen for torture.

What finger splints, tiger chairs and other torture instruments are waiting for them, and who can hold up and not confess?

That's not to say that the prosecutor wasn't authentic.

After all, the prosecutor could have thought of using the scientific method of flies to find blood, instead of directly bringing back several suspects who had a grudge against the deceased to torture them to extract confessions...

In feudal society, the spirit of the rule of law is already shining.

In ancient times, there were "convenient" methods, but in modern times it is more "troublesome".

Modern investigations are all about evidence, and flies are far from reliable evidence.

But...

Lin Xinyi never thought of using flies as decisive evidence against the murderer.

Flying flies to find blood is just a screening method that he came up with to lock down the suspect as soon as possible from more than 100 people when he had no choice but to have limited time.

According to his idea, there might be several passengers in the crowd who could attract flies.

But this did not matter, as long as the few passengers surrounded by flies stayed, and brought to the Metropolitan Police Department for a luminol occult blood test one by one, he could further confirm who the murderer was.

And now, out of more than a hundred, there is exactly one who is liked by the flies.

There is no need to wait for the results of the next examination, the murderer is basically him.

"Don't be stubborn."

"Whether you're getting blood or frosting, science will tell."

Lin Xin could see at a glance that this suspect probably didn't know about the existence of Lumino, so he still had a hint of luck.

So, he simply popularized what the luminol reaction was in front of everyone.

"It's... Can you find reagents to dilute blood stains? ”

Hearing this, the young man's voice trembled slightly.

But after some fluctuations in his eyes, he still replied calmly and clearly:

"That doesn't mean much!"

"I only had a nosebleed in the morning, and I wiped it with my hands."

"So even if you get a blood test from me, it won't prove that I killed someone, right?"

The more this guy spoke, the more firm his tone became, and in the end he even put on an indignant expression, as if he had really suffered some excessive grievance.

"It's simple."

It was not Lin Shinichi who spoke, but the great detective Kudo, who was almost forgotten by everyone:

"Now that the killer has been locked, the evidence is not difficult to find."

"The murderer's purpose at that time was to rob, and all the cash in the deceased's wallet was gone."

"Most of the deceased's cash is now on the murderer, so just send all the banknotes on your body for examination to see if there are any fingerprints and dander left by the deceased when they were touched, and you can confirm whether the murderer is you!"

Kudo Shinichi stood up confidently.

He hasn't played 1 out of 100, and now 1V1 should always be what he's good at.

But the young man, who was regarded as the murderer, instead showed a smile of "I knew":

"Makes sense!"

"Then let's check it - that's all I have on me, you can check it all!"

"If you can't find any fingerprint dander, you'll have to sit down and apologize to me!"

As he spoke, he took out a few coins of pitiful denomination from his shoulder bag and displayed them generously in front of everyone.

"This..."Shinichi Kudo smiled stiffly:

The murderer was clearly prepared.

Most likely, after being forcibly cordoned off the scene, he realized that he might be investigated.

So, this guy secretly hid the stolen money somewhere on the platform, and was going to find a way to get it back after the investigation was over.

It could have been hidden in a trash can, or it could have been a vending machine, but in short, there must have been no money left on him that he had stolen from the deceased.

Moreover, judging by this guy's prepared and fearless appearance, he is afraid that when he touches the banknotes, he is wrapped in clothes and takes them, and maybe he doesn't even leave his own fingerprints on them.

This bastard....

It's not good to use your brain to think of a complicated murder trick, and your mind is all about cleaning up the traces.

How can you be so unlearned?

Mr. Holmes of Heisei was a little depressed.

It was indeed the kind of prisoner he had never dealt with before, and it was an unexpected headache.

"No... There's no way this guy can notice everything! ”

"Look closely... Maybe there will be a breakthrough. ”

Kudo Shinichi riveted his strength, ready to fight with the prisoner.

But... Lin Xinyi spoke up again:

"That..."

"Do you need to find evidence from somewhere else?"

"Do you think that there is no way to identify DNA by washing diluted blood stains, only blood stains that can be seen by the naked eye can identify DNA?"

"Do you think that the blood stains are so small that they are invisible to the naked eye, and the forensic doctor will not be able to extract and test them?"

Lin Xinyi said with a strange expression.

"Huh?" The young man's face changed: "You, what did you say..."

"Can DNA be detected even with such a small amount of blood?"

"Absolutely."

Lin Xinyi looked at the murderer's gaze as if he was looking at a clown with a poor performance:

"DNA extraction and purification of trace samples is the focus of forensic forensics."

"And the luminol reaction does not interfere with the extraction of DNA."

"So, just do a luminol occult blood test on you and take a certain amount of blood-stained dander from the area that fluoresces blue, and you can easily identify who the blood belongs to."

The amount of blood stains in occult blood samples is very small, and the conventional DNA extraction method is limited by the volume of the vector, so it is difficult to obtain the amount of template DNA required for PCR amplification, and it is indeed difficult to obtain good DNA typing.

However, this is not a problem at all, and DNA purification and extraction techniques for microsamples can be of great help.

For example, the magnetic bead nucleic acid purification technology uses nano-scale magnetic beads, which are labeled with a functional group on the surface of the beads, which can adsorb with nucleic acids.

In addition, there is the column purification method, which uses a silica membrane as a specific adsorption material for nucleic acids, and basically does not adsorb to other biological materials, which can ensure maximum recovery of DNA\RNA in the sample while removing other impurities.

In the future, these technologies will mature enough to be made into ready-made purification and extraction kits, as long as you buy them back and follow the instructions step by step.

Of course, Lin Xinyi is not very clear about whether these technologies have been put into use in today's 96 years.

Speaking of which, DNA testing was only used in criminal investigation in 84 years, so DNA purification technology may still be a cutting-edge technology that has not been put into practice.

"I should find an opportunity to learn from Shiho Miyano..."

"She's a biologist and should know better than I do."

Lin Xinyi only uses technology, not researches technology.

Just like the excavator driver probably doesn't know much about the development history of excavator equipment, he really doesn't know much about this aspect.

But it doesn't matter if it hasn't been put into use yet, it's a big deal to collect the blood-stained samples on the murderer's body and store them for 10 years before examining them.

During this time, bioscience and technology developed rapidly, and by the beginning of the 21st century, the detection technology for trace blood stains that are invisible to the naked eye must have matured.

And the criminal prosecution period is 15 years, and this bastard will definitely not escape the punishment of the law.

Merely... This will allow the murderer to go unpunished for a long time.

Justice that is delayed may hardly be considered justice.

Therefore, Lin Xinyi simply didn't care whether these technologies were mature or not, he just put on a face of "you are dead", and said to the young man in a cold tone:

"Idiot, such insight is still alive?!"

"You don't even know—"

"The forensic doctor only needs to remove the blood-stained dander that shows blue light on your body and put it in a beaker, add digestive juice for incubation, and then extract and wash it through the column... The purification column can be used to extract the large system of digestion solution repeatedly through the column, so that the limited DNA in the digestion solution can be concentrated on the column membrane in the process. ”

"Finally, a small volume of pure water is added to elute, and high-quality and high-concentration DNA can be obtained."

In order to enhance the persuasiveness, Lin Xinyi simply explained the detailed operation process:

"When the time comes, the police will naturally find out who the blood on your body belongs to."

"And if the blood found on your hands is the deceased..."

"Heh, do you think there's room for quibble?"

"I... I..."

The young man's face was unusually pale.

He had never heard of any science or technology that could detect occult blood DNA, and he didn't know if it was real.

However, when I heard Lin Xinyi say something at length like that, it was very professional to hear...

Without culture, he can only believe.

Thinking of this, the guy unconsciously broke out in a cold sweat.

He tensed his body nervously as he unconsciously fell backwards.

"You still want to escape?"

Lin Xinyi frowned slightly.

Miss Maolilan clenched her fists, causing a crisp thud.

"I...."

The young man's eyes were full of unwillingness.

But thinking back to the broken wall at the top of the staircase, he still stopped with a grim face:

"I plead guilty."