Chapter 46 Suffering from lack of culture
The murderer finally surfaced.
This man was wearing an ordinary short-sleeved shirt, denim trousers, and a slightly old but clean shoulder bag slung around his waist. He didn't look like a murderer, but like a young office worker passing by.
No one would notice such an ordinary person in the crowd.
But at this moment, this man is like salt melted in water, being exposed by the sun of justice.
More than a hundred pairs of eyes were all fixed on him, leaving him no longer able to escape.
"I"
The young man who was regarded as the murderer by Lin Xinyi had a stiff expression on his face.
But in the end, he responded:
"Are you kidding me?!"
"You say I'm a murderer because of a few flies? I just ate ice cream not long ago and my hand got the buttercream frosting that fell from the ice cream. Is this normal?"
The young man defended himself so excitedly.
"Haha." Lin Xinyi gave him a disdainful smile.
Indeed, the trick of flying flies seeking blood is actually very limited and very easy to be interfered with.
Things like icing sugar, butter, honey and the like that are common in life can also attract flies. The presence of flies does not necessarily mean that there is blood on the person.
Now is different from ancient times.
In ancient times, it was possible to rely on flies to search for blood to make the murderer bow his head and confess, probably because
If he does not plead guilty, the murderer will be taken back to the Yamen and beaten.
What kind of torture instruments such as splints and tiger benches are used up? Who can resist confessing?
This cannot be said to be unreasonable.
After all, the prosecutor could have thought of using the scientific method of flying flies to search for blood to investigate the case, instead of directly bringing back several suspects who had a grudge against the deceased and tortured them to extract confessions.
In feudal society, the spirit of the rule of law was already shining brightly.
There were "convenient" methods in ancient times, but modern times are more "troublesome".
In modern criminal investigations, everything depends on evidence, and flies are far from reliable evidence.
but
Lin Xinyi never thought of using flies as conclusive evidence pointing to the murderer.
Flying for blood was just a screening method he used to identify suspects as quickly as possible among more than 100 people under forced circumstances and limited time.
According to his thinking, there might be several fly-attracting passengers in the crowd.
But it had no effect at all. As long as the few passengers surrounded by flies stayed and were taken to the Metropolitan Police Department for luminol occult blood tests one by one, he could further confirm who the murderer was.
And now, out of more than a hundred people, there happens to be only one person that the fly likes.
There is no need to wait for the next test results, the murderer is basically him.
"Stop resisting."
"Whether you got blood or frosting, science will tell us."
Lin Xin could tell at a glance that the suspect probably didn't know the existence of Luminol at all, so he still had a sense of luck.
So, he simply explained what the luminol reaction is in front of everyone.
"Can, can we find a reagent for diluting blood stains?"
Hearing this, the young man's voice trembled slightly.
But after some fluctuations in his eyes, he still answered calmly and clearly:
"That doesn't mean anything!"
"I just had a nosebleed in the morning, and I wiped it with my hands."
"So even if blood is tested from my body, it doesn't prove that I committed murder, right?"
The more this guy spoke, the firmer his tone became, and in the end he actually had an indignant expression on his face, as if he had really been unfairly wronged.
"this is very simple."
The one who spoke was not Lin Shinyi, but the great detective Kudo who had been almost forgotten by everyone:
"Now that the murderer has been identified, the evidence will not be difficult to find."
"The murderer's purpose was robbery, and all the cash in the deceased's wallet was missing."
"Most of the deceased's cash is on the murderer's body now, so just send all the banknotes on your body for inspection to see if there are any fingerprints or skin flakes left on them when the deceased touched them, and you can confirm whether the murderer is you!"
Kudo Shinichi stood up confidently.
He has never played 100 pick 1, and now 1V1 should be where he is good at.
But the young man who was regarded as the murderer showed a smile that said "I knew it":
"That makes sense!"
"Then come and check - I only have so much money on me, you can take it all and check it!"
"If you can't find any fingerprints and dander, you have to use the soil seat to apologize to me!"
As he spoke, he took out a few coins of pitifully small denominations from his shoulder bag and displayed them openly in front of everyone.
"This" Kudo Shinichi's smile froze:
The murderer was clearly prepared.
He probably realized that he might be investigated after he was forcibly blocked at the scene.
Therefore, this guy secretly hid the stolen money in an inconspicuous place on the platform, and planned to find a way to get it back after the investigation was completed.
It might be hidden in a trash can, or it might be in a vending machine. In short, there must not be any banknotes snatched from the deceased left on him now.
Moreover, judging from the way this guy was prepared and confident, he probably wrapped the money in his clothes when handling it, and maybe he didn't even leave his fingerprints on it.
This bastard
Instead of thinking about a more complicated murderous plot, all my thoughts were spent on cleaning up the traces.
How can you be so ignorant?
Mr. Holmes from Heisei was a little depressed.
This was indeed a type of prisoner he had never dealt with before, and it was unexpectedly troublesome.
"No, this guy can't possibly notice every aspect!"
"If you look carefully, there may be a breakthrough point."
Kudo Shinichi was full of energy and prepared to battle wits and courage with the prisoner.
But Lin Xinyi spoke up again:
"that"
"Is it necessary to look for evidence from other places?"
"Do you think that DNA cannot be identified by washing and diluting blood stains? Only blood stains that can be seen with the naked eye can identify DNA?"
"Do you think the blood stains are so small that they can't be seen by the naked eye, so forensic doctors can't extract them for examination?"
Lin Xinyi said with a strange expression.
"Uh?" The young man's face changed: "W-what did you say?"
"Can DNA be detected from such a trace amount of blood?"
"sure."
Lin Xinyi looked at the murderer like he was looking at a clown who performed poorly:
“The extraction and purification of DNA from trace samples has always been the focus of forensic evidence research.”
"And the luminol reaction will not interfere with the extraction of DNA."
"So, as long as you do a luminol occult blood test and then take a certain amount of blood-stained skin scrapings from the area that shows blue fluorescence, you can easily identify who the blood belongs to."
The blood trace content of occult blood test materials is very small. Conventional DNA extraction methods are limited by the volume of the carrier and cannot obtain the amount of template DNA required for PCR amplification. It is indeed difficult to obtain better DNA typing.
But this is actually not a problem at all. DNA purification and extraction technology for trace amounts of test materials can be of great help.
For example, magnetic bead nucleic acid purification technology uses nanoscale magnetic beads. The surface of these magnetic beads is marked with a functional group that can adsorb nucleic acids.
In addition, there is column purification method. The nucleic acid purification column used in this technology uses silica gel membrane as a specific adsorption material for nucleic acids, and basically does not adsorb other biological materials. It can ensure the recovery of DNA\\RNA in the sample to the greatest extent, and at the same time remove Other impurities.
In the future, these technologies will be mature enough to be made into ready-made purification and extraction kits. Just buy them and follow the instructions step by step.
Of course, Lin Xinyi is not sure whether these technologies have been put into use in 1996.
Speaking of which, DNA testing only began to be used in criminal investigations in 1984, so DNA purification technology may still be a cutting-edge technology that has not been put into practice.
"We should look for opportunities to learn from Miyano Shiho"
"She is a biologist and should know better than me."
Lin Xin only uses technology, not researches it.
Just like the excavator driver, he 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 even if it hasn't been put into use yet. The worst thing is to collect the blood-stained test materials from the murderer first and save them for 10 years before inspecting them.
During this period, biological science and technology developed rapidly. By the beginning of the 21st century, the detection technologies for trace amounts of blood stains invisible to the naked eye must have matured.
The criminal prosecution period in Japan is 15 years, so this bastard will never escape legal punishment.
It's just that this will allow the murderer to remain free for a long time.
Delayed justice may hardly be justice.
Therefore, Lin Xinyi simply didn't care whether these technologies were currently mature or not. He just put on a "you're dead" face and said to the young man in a cold tone:
"Idiot, you still hold on to such knowledge?!"
"You probably don't know at all—"
"Forensic doctors only need to take out the blood-stained skin shavings that show blue light on your body and put them into a beaker, add digestive juice for incubation, and then extract and wash them through the column. Then they can use the purification column to repeatedly pass the large system of digestive juice through the column for extraction. , allowing the limited DNA in the digestion solution to be concentrated onto the column membrane during this process."
“Finally, by adding a small volume of pure water for elution, you can obtain high-quality and high-concentration DNA.”
In order to enhance his persuasion, Lin Xinyi simply explained the detailed operation process:
"At that time, the police will naturally identify who the blood on your body belongs to."
"And if the blood found on your hands is that of a deceased person"
"Oh, do you think you still have room for quibbles?"
"me"
The young man's face was unusually pale.
He has indeed never heard of any scientific technology that can detect latent blood DNA, and he does not know whether this scientific technology actually exists.
However, when I heard Lin Xinyi speak in such a long way, it sounded very professional.
Being uneducated, he could only believe it.
Thinking of this, the guy broke into a cold sweat unconsciously.
He tensed his body nervously and backed away unconsciously.
"You still want to escape?"
Lin Xinyi frowned slightly.
Miss Mao Lilan clenched her fists, causing a crisp sound.
"I"
The young man's eyes were full of unwillingness.
But thinking back to the smashed wall at the entrance of the stairs, he still stopped with a livid face:
"I plead guilty."