Coroner Coroner

"There's a hole the size of an arm in the center of the umbrella..."

Asai Cheng practically took the transparent umbrella out of the cabinet with gloved hands:

"I understand!"

"The murderer must have been wearing gloves, sticking the pistol through the hole in the canopy before firing."

"In this way, the shooting residue splashed out when the gun is fired is all blocked by the gloves and the umbrella!"

"That's what the murderer used to evade the smoke test."

"That's right." Lin Xinyi encouraged without hesitation, but poured cold water on him mercilessly:

"But it's useless to know the technique..."

"Look, are there any fingerprints left on the umbrella?"

"Or, can you find the gloves he was wearing?"

"This..." Naruto Asai was slightly taken aback.

He immediately took a magnifying glass to observe the umbrella body carefully, and then searched the room carefully:

"No...no fingerprints found on the umbrella."

"I couldn't find that pair of gloves in the room either. It may have been disposed of by the murderer in some way."

"Then this umbrella can't be used as evidence..."

"Even, it has no way to prove that this utility room is the scene where the murderer shot and killed."

Lin Xinyi sighed lightly:

To prove that Takashi Matsuo is the murderer, it must first be proved that the murderer used the technique of shooting down on the 9th floor to kill.

To prove that the murderer used this method to kill people, in addition to the bullet holes found on the ground, it must also be proved that the utility room on the 9th floor was the scene of the murder.

The utility room on the 9th floor is the scene of the crime, so far they have only deduced it through the facts of the case.

To prove this point, we have to come up with real evidence.

"Let me see..."

"The killer stuck his head out of the window and shot down."

"The cartridge case must have been thrown out of the window and onto the road. It cannot be found in this room."

"However, the killer used an automatic pistol."

"And the smoke from the automatic pistol is in the shape of a downward semicircle."

"So, even if the umbrella cover blocked the shooting smoke from being sprayed backwards on the murderer, there must still be some shooting smoke sprayed on the wall outside the window."

Lin Xinyi quickly thought of a way to prove that the utility room on the 9th floor was the scene of the crime:

"There must be residue left by the shooting on the window wall of this utility room!"

"As long as you extract the shooting residue on the outer wall of the window and do a smoke test, you can prove that this is the scene of the murderer's shooting!"

"Miss Maori, you will be responsible for extracting the shooting residue!"

"Yeah." Maurilan nodded.

"By the way, do you know which method to use to extract it?" Lin Xinyi asked specifically.

Unsurprisingly, the good student Mao Lilan gave a perfect answer:

"The outer wall of the window is an object with a relatively flat surface, but is relatively uneven, and has a lot of pollution and a low finish."

"To extract the shooting residue on this kind of object, AC paper extraction method should be used."

AC paper is a film made of special fibers, with strong adhesion, good film strength and permeability, and is suitable for extracting shooting residues on uneven surfaces.

Answering Lin Xinyi's question, Mao Lilan quickly opened the on-site investigation box, and began to operate according to the knowledge he had learned.

She first held a piece of AC paper with tweezers and soaked it in acetone liquid.

After the AC was soaked and softened, Mao Lilan carefully took it out and pasted it on the outer wall of the window where there might be shooting residues.

Then, she carefully attached the second AC sheet, pressing it lightly with her fingers.

The AC paper covering the wall dried quickly, and Mao Lilan gently peeled it off the wall and kept it, and the shooting residue on the wall was also extracted.

And while she's busy extracting gunshot residue from the wall...

Hayashi Shinichi and Asai Chengshi were not idle either.

They temporarily turned off the lights in the utility room to create a dark room without the interference of light sources.

Then, he took out the multi-band light source flashlight from the investigation box—after Lin Xinyi took charge of the forensic class, the Metropolitan Police Department finally purchased this practical investigation tool.

Lin Xinyi adjusted the light source of the flashlight to a wavelength of about 440nm, and began to look for traces in the scene that were difficult to find with the naked eye together with Naomi Asai.

Under this wavelength of light, most of the body fluid spots will be excited to emit a faint natural fluorescence.

"found it…"

"A dried saliva stain on the stacked cardboard boxes by the window!"

Lin Xinyi found an important clue.

Asai Chengshi took a closer look at the saliva stain, and asked a little worriedly:

"Mr. Lin, could these saliva spots be left by the murderer?"

"Nine times out of ten."

Lin Xinyi pointed to the saliva stains and said:

"Look, this series of saliva stains are all in a spray-like distribution."

"Why is it spraying? Because when they leave the human body, they have a jetting power."

"And that drive is..."

"Sneeze? Or, cough?"

Asai Chengshi quickly reacted:

"By the way, that guy Matsuo happened to have the flu!"

"He has been coughing and sneezing, and these spots of saliva are probably sprayed out accidentally when he committed the crime!"

Thinking of this, Asai Chengshi couldn't help but said happily:

"Mr. Lin, isn't that enough?"

"There is DNA in the saliva, which can prove that Matsuo has been here."

"There are shooting residues on the outer wall, which can prove that this is the scene of the murderer's shooting."

"In that case, wouldn't it prove that Matsuo is the murderer?"

"It's not that simple..." Lin Xinyi shook his head:

"What if he quibbles, saying that he has been here during the day, or has been here in recent days?"

"This..." Asai Chengmi choked slightly.

"It can prove that Matsuo has been to the crime scene, but it can't prove that he is the murderer who shot here."

And Lin Xinyi sighed deeply, and continued:

"So, what we have to figure out now is that..."

"At the time when the deceased was shot, Matsuo was at the crime scene."

Chapter 164 Time Calculation Accurate to the Minute

Hearing Hayashi Shinichi's exclamation, Asai Narumi couldn't help being entangled——

Indeed, so far, the only evidence found at the scene is:

Spit stains on cardboard boxes, gunshot residue on exterior walls, a clear umbrella with no fingerprints.

The shooting residue and umbrella can prove that the utility room on the 9th floor is the scene of the murderer's shooting.

Saliva spots can prove that Takashi Matsuo has been here.

However, adding these two points together, it cannot be deduced that Takashi Matsuo is the murderer who shot and killed Suwa in this utility room.

After all, "Matsuo has been here" does not mean "Matsuo has been here at the time of the incident".

Takashi Matsuo can say that he has been here for the past two days, and accidentally sneezed, leaving traces.

"so what should I do now?"

Asai Narumi frowned slightly, and asked about Lin Xinyi.

But Lin Xinyi spread his hands helplessly:

"There are many ways, but it all depends on luck..."

"Expect to find more evidence in other places in the building in the future, for example, the gloves hidden by the killer."

"Or, I hope that the first search section can 'show off its power' and find out the way Matsuo purchased the gun, proving that the gun belongs to Matsuo."

"Or, rely on the existing evidence to prove that Matsuo is suspected of committing a major crime, and take him back as a suspect for interrogation. Then use interrogation psychology to break through his psychological defense bit by bit."

In the actual case detection, not every case is so easy to find strong evidence, which can be solved completely by trace inspection and forensic medicine.

It is often the technical detective who cooperates with the investigation and interrogation, and the division of labor and cooperation between the two complement each other to form a complete chain of evidence and bring the murderer to justice.

only…

In reality, it was Lin Xinyi's capable criminal police colleagues who were in charge of the investigation and interrogation.

But now, his teammates are searching for class one.

Thinking of this, Lin Xinyi suddenly lost confidence:

"Let's try again..."

"Can you find stronger evidence?"