Coroner Ke Xue

The tape extraction method is suitable for extracting dust fingerprints on smooth object surfaces.

When the contrast between the dust fingerprint and the object is not obvious like now, using tape to stick it on can avoid the influence of the object.

At Lin Xinyi's request, the Seyu family's servant quickly delivered a roll of wide tape.

The Seyu family has a large business, and the utility room is wider than the living room of an ordinary family. All kinds of daily necessities are always ready.

So, in the nervous eyes of Mr. Seyu,

Lin Xinyi first used his own tape to extract the fingerprints he left.

The extraction process is also very simple

The principle and operation are probably similar to the way elementary school students use tape to remove typos in their homework books.

Spread the wide tape evenly on the glass, press it firmly, and then carefully peel it off.

The fingerprint made of dust was completely stuck to the wide tape.

"But you still can't see clearly?"

The police officers asked with concern.

Although the handprint is printed on the tape and is convenient to hold, it is still a bit unclear.

"It's okay, have you forgotten what you just did to find the fingerprints?"

"We can also use this light transmission enhancement method, and it is more convenient to operate."

As he spoke, Lin Xinyi gently placed the wide tape with fingerprints on it in front of the black body of the TV in the guest room.

When the background color is changed, the contrast becomes more obvious.

The fingerprints on the tape suddenly became much clearer.

"Here, flashlight, then use a 45-degree angle to light it from the side."

Lin Xinyi continued to guide several rookie operations:

But this time, as soon as the light was turned on, the dust fingerprints on the wide tape appeared more clearly against the black background.

Due to the particle nature of dust, dust fingerprints are opaque and diffusely reflective, while the tape used to capture dust fingerprints has better light transmittance.

Therefore, when the light source is irradiated at a 45-degree angle, the part of the tape with dust attached will be in a diffuse reflection state under the light, and the part of the tape without dust will be in a specular reflection state under the light, thus effectively strengthening the fingerprint. Contrast.

“Now we can see it clearly!” the police officers from the forensics department shouted excitedly.

"Take photos and record them." Lin Xinyi calmly ordered them to do the only thing they were good at.

In this way, the police officers from the forensics department took photos of the fingerprints and recorded them, and the wide tape with the fingerprints on them was also well preserved.

"This this"

Seba Tundoku's face changed slightly, and then he pretended to be calm and asked:

"With this handprint, we can catch the criminal, right?"

“It can make a big difference.”

"Because age, gender, weight, bone and other factors vary, the contours of each person's hand will be slightly different."

"Although there is no palm print that can accurately lock the identity, by comparing the outline of the hand, at least the scope of the investigation can be greatly narrowed."

Lin Xinyi explained with caution.

"Oh, I'm just narrowing it down."

Mr. Seba's tortured heart was able to breathe again.

But he didn't expect that Lin Xinyi was like the master of Landlords who had 17 cards in his hand. Although he had thrown the bomb, the good cards in his hand were far from finished:

"It's still a bit reluctant to rely on fingerprints to find the murderer."

"So I will use another method to extract the murderer's footprints."

"Footprints?"

Several forensic police officers asked curiously:

"Wide tape can also detect and extract footprints?"

"No, we can't use tape this time." Lin Xinyi shook his head slightly:

The adhesive tape is so strong that it can absorb almost all the dust on the object surface.

The glass window was cleaned by the servants every day, so it was clean and free of dust.

Dust fingerprints can be extracted directly from the glass using tape without being interfered by other dust.

But the footprints are different.

Footprints may be on the floor, walls and marble handrails

Those places are rougher than the glass and covered with more dust.

If you use a highly adhesive tape to stick it directly, you may end up with only a piece of tape covered with dust.

Therefore, if you want to extract footprints, you must use a more technological method.

"that"

Lin Xinyi looked around in the guest room.

Finally, he stared at the square, old-fashioned TV set:

"Tear this TV apart and remove the black chassis panel from the side of the TV."

"Eh?" None of the police officers responded:

Why dismantle someone else’s TV when the TV can also be used to solve crimes?

"Just tear it down!"

"The police department will pay for the damage to my forehead!"

Lin Xinyi urged without explanation.

As a result, several young police officers quickly dismantled the TV.

Seba Tundoku wanted to stop him very much, but he couldn't speak out - as a chaebol boss, it was impossible for him to be reluctant to part with a TV.

Soon, the television was disemboweled.

The flat and wide black fuselage side panel was also carefully removed by the police officers.

"Then what?"

Looking at this big black plastic plate, everyone was confused.

But Lin Xinyi pointed at the plastic plate that had just been removed from the TV and ordered the police officers:

"You take a few pieces of clothing or other textiles and rub them against this plastic plate."

"Friction?" The police officers were slightly startled.

"friction!"

Lin Xinyi felt like he was teaching primary school students.

And if you think about it carefully, what he taught about breathing, lighting, and tape seems to be something that elementary school students can do.

Even the trick being used now is within the knowledge of primary school students:

"Friction generates electricity, understand?"

“Use a friction method to statically charge the plastic sheet, and then lay the static-charged plastic sheet in areas where there may be dust footprints.”

As a forensic doctor, Lin Xinyi will appear at the scene every time with his colleagues who are also technical investigators.

The equipment they use most to extract dust footprints is the electrostatic adsorber.

There are no ready-made electrostatic adsorbers now, so Lin Xinyi can only try to let these police officers use local methods and materials to create electrostatic adsorption devices through human flesh friction.

“When a small, non-static object is close to a static-charged object, due to the phenomenon of electrostatic induction, the end close to the static-charged object will sense the opposite electrical property to the static-charged object, which will cause the tiny object to be attracted and attached to the static-charged object. on objects.”

Lin Xinyi briefly explained the principle of electrostatic adsorption:

"So as long as you lay the electrostatically charged plastic board where there may be dust footprints, the dust on the object will be adsorbed to the plastic board due to the electrostatic adsorption effect."

"The dust on the object is transferred to the black plastic plate. Because the background color difference is enhanced, the dust footprints that were originally difficult to distinguish with the naked eye can appear relatively clearly."

He explained at length.

I don’t know if the police officers understood it, but they were busy in full swing anyway.

A few young men took off their coats and rubbed hard against this black plastic board. After a while, the board almost started to burn.

Then, following Lin Xinyi's instructions, they tried to spread the plastic sheets that had been charged with static electricity on the guardrail handrails of the balcony.

This guardrail handrail is made of marble and has a relatively wide upper edge, which is very suitable for using your feet when climbing.

Therefore, Lin Xinyi regarded it as the primary target of suspicion for possible footprints.

And the results were not unexpected.

The police officers laid the black plastic board on the marble handrail and waited for a while before picking it up.

An almost complete dusty shoe print had clearly appeared on the black plastic board.

"It's over!"

Seeing this, Seba Tundoku's face turned green:

The previous handprints only made him feel dangerous, but now the shoe prints were truly deadly!

Because his left foot is still wearing the shoe from that time!

At that time, he was anxious to appear in front of everyone, and there was a murder at home. The servants would definitely come to his room to look for him soon.

Therefore, his time alone after committing the crime was very short.

In such a short period of time, Seba Tatsunoku needed to jump from the balcony to the opposite wall with a rope, crawl back to his room, hide his gloves and mask, change into clean clothes, and re-wrap his right leg in plaster. .

Having to do so many things in 2 or 3 minutes is really difficult for an old man like him.

As soon as time became tight, Seba Tundoku no longer bothered to change into the most inconspicuous shoes——

After all, he made a point of checking when he left the scene that he didn't leave any shoe prints.

But I never expected it

Lin Xinyi actually used a trick of elementary school level knowledge to find the shoe prints that he could not see with the naked eye!

Thinking of this, Seba Tundoku's heart was already beating wildly.

He could only pray that Lin Xinyi would let him go, as a "disabled person", and not come to him with the fingerprints and footprints.

But just then

"Handprints and footprints were found."

"Then Mr. Seha Tundoku, you should be the first to compare!"

Lin Xinyi turned around and glanced at Seba Tundoku in the wheelchair.

"W-what?!"

Mr. Seyu's face completely lost all color:

"Why do you want me to investigate?"

He was pretending to be a disabled person, so how could Lin Xinyi still think of him first? !

Was his disguise discovered from the beginning?

Lin Xinyi’s answer is:

"Because you talk too much."

"Besides, I was still quite unhappy after being ridiculed by you just now."