TPODN Chapter 51

Secret room.

Wang Linfei felt a surge of unprecedented challenging spirit.

This was because the culprit who had achieved this ingenious crime had left him, a self-proclaimed expert in deduction, completely clueless.

Wang Linfei had never tackled a locked-room murder before. He knew that whether he wanted to become a criminal investigation expert in the bureau or a self-proclaimed deduction expert, he had to pass the “locked-room murder” test.

Everything was arranged to frame Minister Zhao Menglin! From the initial intuition to the growing certainty now. Even if the murder weapon was found, assuming Minister Zhao Menglin was the murderer would lead to too many inconsistencies.

Locked-room murder techniques.

The possible methods had been narrowed down. There were three entrances and exits that could access the chairman’s office, leaving only the door.

In other words, the method used by the murderer was undoubtedly exploiting the blind spot of the surveillance camera. The police in Huangle District were also pursuing this lead.

Wang Linfei walked to the cabinet in his office, took a zip-lock bag from the small drawer above. Inside was a thin squirrel hair, the same squirrel hair found in Chairman Zhou Runmin’s office. He had seen this kind of squirrel hair so many times that he could recognize it at a glance.

What was the purpose of this magical squirrel hair? Outsiders wouldn’t know, but for a criminal investigation insider like Wang Linfei, it was all too familiar.

When collecting fingerprints, the police identification department uses various methods depending on the situation at the scene. For example, using vaporized iodine adhesion, or the Ninhydrin method that reacts with amino acids, as well as cyanoacrylate, which is often used as an adhesive. For blurred latent fingerprints, fluorescent powder can be applied first, and then irradiated with an Argon laser. If the fingerprints are attached to the human body, ruthenium tetroxide developed in Japan is used.

However, throughout history, the most commonly used method by criminal investigators is the traditional powder method. This method involves first applying various powders such as aluminum, red pigment, or copper, or sticking spores of ferns called lycopodium on the fingerprints, and then using a brush called a fingerprint brush to remove unnecessary powder.

Throughout the entire operation, in order not to damage the fragile fingerprints, the most suitable material for making fingerprint brushes is squirrel hair.

The reason why Wang Linfei was able to find squirrel hair in the chairman’s office was because Wang Linfei suspected that the police colleagues from the Huangle District police station also suspected the surveillance cameras.

In other words, the Huangle District police at least suspected that the surveillance cameras had been tampered with.

At this moment, Wang Linfei picked up his phone, preparing to call Mu Ran, the captain of the Huangle District police station.

Mu Ran and Wang Linfei were old friends.

“Hello?”

An impatient, low reply, sounding like a beast just awakened.

“Is this Captain Mu of the Fengyun City Huangle District Police Station? This is Wang Linfei, deputy captain of the ‘Special Criminal Investigation Unit’ of the city bureau.”

“Oh, it’s you, Detective Wang, ah yo, just woke up. Had a few drinks yesterday.”

“Captain Mu can still take it easy outside of such a complicated case. I envy you.”

“I want to live a free life. I don’t want to be tied down by cases.”

Captain Mu Ran’s voice was loud, deep, and threatening. Someone with less courage might be scared witless. But in Wang Linfei’s ears, he knew that Mu Ran was in a good mood.

“Back to business, any discoveries, Captain Mu?”

“Isn’t this our job? Our team is assisting your police station in handling the case. If you want to know, shouldn’t your people have told me everything, Detective Wang?” Captain Mu shouted.

“I’m afraid there are some things that only you know, Captain Mu,” Wang Linfei said bluntly.

“What exactly do you want to know?”

“The evidence the police are using to determine that Zhao Menglin is the murderer.”

“Oh, Captain Wang, you’re wronging me. You don’t have any grudges against this Zhao Menglin, nothing at all. It’s just because the crime scene is a locked room, and no one else could have gotten in.”

“However, some of your people should have questioned it, right?” Wang Linfei said.

“Questioned? What’s wrong?” Mu Ran was probably still half-asleep, unable to understand Wang Linfei’s words.

“Stop pretending. What do you think? Is Zhao Menglin a suspect?” Wang Linfei chuckled coldly.

There was a pause of about a second in the conversation.

“You can’t say that, but just because he’s a senile old man, he might not remember committing the crime,” Captain Mu said.

“What about the fingerprints? You definitely couldn’t find them, right?” Wang Linfei wanted to try to get some information. Captain Mu’s voice immediately changed.

“How did you know about the fingerprints?”

“Nonsense. Your case team conducted an investigation at the scene and saw quite a few things. How much did you drink yesterday, Captain Mu?” Wang Linfei said.

He originally wanted to ask directly, but Wang Linfei knew Mu Ran’s personality too well. If he used guiding techniques to make him feel like he was the one asking, he would be more forthcoming.

“I’ve seen every corner of the entire floor. Although the crime scene is in the chairman’s office, that office is connected to the office of the director of product planning and the office of the general manager, right? Logically, you should have sealed off all three offices to preserve the scene, shouldn’t you?”

“But, the three offices have already been thoroughly examined…Hey! Don’t change the subject! How did you notice the fingerprint on the doorknob?”

Minister Zhao Menglin’s office, then the doorknob. Everything was connected.

Wang Linfei continued, “First, Zhao Menglin should rarely open the door to Manager Liu’s office because their relationship isn’t very good. Besides, he himself doesn’t remember the last time he touched the doorknob. Second, that doorknob has been wiped quite frequently.”

“How do you even know that?” Mu Ran knew that Wang Linfei was very skilled and thorough in investigating cases, but he didn’t expect him to be this thorough.

“The surface of that doorknob isn’t gold-plated, but genuine brass. It should be an imported antique, right? If the surface of brass products isn’t specially treated, it will quickly oxidize into a dull brown color. If it’s not wiped frequently, it’s impossible to maintain its current color.”

“Hmm, Detective Wang, you’re still so observant,” Mu Ran said.

“Based on the above two points, the possibility of Zhao Menglin’s fingerprints remaining on the doorknob of the door leading from the product planning department director’s office to the general manager’s office before the crime should be very slim.”

“So what?”

“Assuming Zhao Menglin is innocent, then Zhao Menglin’s fingerprints shouldn’t be found on the doorknob. And in the absence of fingerprints, it will be much more beneficial to Zhao Menglin, because if you want to go back and forth between the product planning department director’s office and the chairman’s office while avoiding the surveillance cameras, you can only choose to go through the general manager’s office.”

At this moment, Captain Mu Ran began to think.

“But, can the absence of fingerprints on the doorknob be evidence of innocence? Even if they couldn’t be wiped off later…maybe he wore gloves,” Captain Mu said after thinking for a while.

“Did my people find gloves?” Wang Linfei asked.

“No. But, even if you don’t find gloves, you can just wrap your hand in a handkerchief.” Listening to Mu Ran’s excuses, which seemed a bit strange, Wang Linfei couldn’t help but feel that something was amiss.

Why did his reasoning change from ‘wearing gloves’ to ‘wrapping his hand in a handkerchief’? The most natural assumption should be to hold the doorknob with a bare hand and then wipe off the fingerprints with a handkerchief.

No! Mu Ran just said, ‘Even if they couldn’t be wiped off later…’ Why was he so sure that the murderer couldn’t wipe the doorknob?

Wang Linfei tried to continue to trick him.

“Do you know what left the fingerprints that remained on the doorknob?”

Mu Ran couldn’t help but click his tongue.

“You even noticed that. It has been determined that it was the secretary who touched the doorknob early that morning, and the time should be before Zhao Menglin entered the company.”

Wang Linfei barely restrained himself from exclaiming. Zhao Menglin’s secretary’s name was Jiang Kefan, right? Her fingerprints were actually left on the doorknob after the crime?

“Why did Jiang Kefan need to enter Manager Liu’s office?”

“It seems that she originally took some documents that needed to be approved to Zhao Menglin’s desk, but accidentally mixed in the documents that were to be given to General Manager Liu Ziqi. We also interrogated Liu Ziqi’s secretary, and there were no suspicious circumstances.”

“Which side of the doorknob had fingerprints?”

“Both sides had them.”

“How clear were the fingerprints?”

“What do you mean? Very complete. The fingerprints of the secretary’s thumb, index finger, and middle finger can be completely collected from both sides of the doorknob.”

“If that’s the case, don’t you think it’s a bit unnatural?”

“What do you mean?”

“If the fingerprints left by the secretary happened to be in the shape of completely grasping the doorknob, then Zhao Menglin would have to not only try to avoid leaving his own fingerprints but also deliberately twist the doorknob in a way that he wouldn’t normally touch it.”

“He just didn’t want to leave his own fingerprints.”

“But, how could he avoid the secretary’s previous fingerprints? He doesn’t have X-ray vision, can he see the latent fingerprints?”

Mu Ran was speechless, Wang Linfei continued to deduce:

“Besides, such a crime scenario is clearly contradictory to what you just said about committing the crime in a half-awake state.”

“Stop nagging! We know these little things too, don’t look down on the police in Huangle District!” Mu Ran burst out in anger.

“Even if there are some inconsistencies, you can’t wash away the suspicion, right? There’s no one else but that old man!” Mu Ran concluded.

“Then, what about the door between the general manager’s office and the chairman’s office? There shouldn’t be Zhao Menglin’s fingerprints on that door, right?”

A sigh of resentment.

“…Alas, there weren’t any fingerprints on that door,” Mu Ran said, feeling that he couldn’t win against Wang Linfei’s reasoning. He felt that he had to admit defeat.

As expected, Zhao Menglin was framed by the real murderer, which is why the crime scene was designed as a locked room.

“Hey, it may be too early to rule out the possibility of other people committing the crime at this stage,” Wang Linfei said.

“What do you mean? Are you saying the chairman was killed by someone else?” Mu Ran said.

“The police have suspected that, right?”

“What are you talking about?”

“We collected the fingerprints on the surveillance cameras, didn’t we?”

Mu Ran was speechless.

“How would I even know that…Wait, there should be aluminum powder left on the camera, right? You’re right, right?”

“Yeah, that’s about it. Was it you who thought of suspecting that the surveillance cameras had been tampered with?”

“No, it was our director. Because he couldn’t accept that the old man Zhao Menglin was the murderer until the very end. However, the result was still in vain. Not only did we not find any fingerprints on the camera, but there was also no possibility of the wiring being cut in the middle,” Mu Ran sighed.

At this moment, Wang Linfei felt a sense of shock.

“Are you sure?”

“Of course. There’s no place in that building where the murderer could hide and do anything. To be on the safe side, we even pulled out all the long wires and checked every centimeter. As expected, there wasn’t even a mosquito bite.”

This time, it was Wang Linfei’s turn to be speechless. He originally thought that the police in the Huangle District police station had locked on Zhao Menglin as the murderer from the beginning, but he didn’t expect them to have investigated so thoroughly.

“Were there any unusual things in the video recordings during the time of the crime?”

“Hey! Didn’t I tell you? There was nothing wrong with the camera and the route!”

“But, what about the video itself? Even before the time of the crime, wasn’t there any situation where the image was interrupted or skipped frames?”

“Hmm?”

His way of asking seemed a little too aggressive, and Mu Ran’s tone changed again.

“The consultation up to this point is free, after all, I owe you a few meals. However, if you want to continue asking, unless I treat you to a few more barbecues.” Through the phone, it felt like a stench was coming over.

“…Your director is Sun Li, right? He also thinks that Zhao Menglin isn’t the murderer?” Wang Linfei changed the subject.

“Yeah, that old guy is super stubborn too. Because he’s already given up on getting promoted and making a fortune, he’s arguing with the deputy director and others.”

“Then, if he can successfully overturn the assumption that Zhao Menglin is the murderer, wouldn’t Director Sun’s stock rise?”

“You can say that. Then Deputy Director Wei Qing would lose face,” Mu Ran sighed.

“If this matter is handed over to you, wouldn’t it be a great advantage? This isn’t just a few barbecue meals, Captain Mu Ran,” Wang Linfei said meaningfully.

At this moment, Mu Ran’s voice was mixed with suspicion.

“What does that mean? Are you trying to overturn the assumption set by the police?”

“Maybe.”

“Really?”

“Just that, you need more information.”

“Everyone wants information, we scratch each other’s backs, I said I’ll trade a few barbecues for it.”

“You don’t have any useful information to exchange at this stage. Let me check on the video recording first and tell you later. Anyway, it won’t hurt me.”

The two fell into a silence, probably calculating the gains and losses.

“…Okay, for the sake of our long friendship, I have to try even if I know it’s not going to work. I want to know if the video recording has any unnatural anomalies, or if there’s any possibility of it being tampered with,” Mu Ran said.

“Yeah, I’m counting on you. If I find anything here, I’ll notify you immediately,” Wang Linfei said excitedly, seeing that he had gotten Mu Ran on his side.

“Hmm.”

The conversation ended abruptly.

Having secured Mu Ran as his source, Wang Linfei crossed his arms and fell into thought.

So far, it was known through investigation that the only way to enter the locked room was through the three doors facing the corridor. However, at the time of the crime, these three doors were under surveillance by surveillance cameras.

In that case, the murderer must have tampered with something to deceive the surveillance cameras.

But, don’t forget that the camera’s image is first viewed by the security guards before being recorded on the tape. In other words, the current situation is not. You only need to deceive either the human eye or the machine. Humans and machines naturally have their own weaknesses, but as long as both are used together, the degree of preparedness will be immediately improved by combining their strengths.

However, if the method used here is to switch the image captured by the surveillance camera with a fake image… as long as the image is faked at the entrance, both humans and machines can be deceived at the same time at the exit.

The problem is, the specific method initially thought of was to cut off the wiring of the surveillance cameras.

First, you need to find a blind spot in the wiring configuration of the building, a space that won’t be discovered. When the recording stops at night, you can cut the wiring without leaving any traces. Then, as long as you open the connection to the surveillance camera, you can switch the image from the surveillance camera to the recorder at any time. On the other hand, you have to select a segment of the corridor with only one person in it from the prerecorded tape and make a backup tape. Of course, the brightness and angle of the light will also be different depending on the time of day or the season, and these have to be noted.

After that, before committing the crime, use a switch to switch to the copied image being played from the recorder, and the murderer can swagger in and out of the chairman’s office.

However, the biggest disadvantage of this method is that it will leave decisive evidence in the wiring. It’s not enough to pierce the outer layer of the wires with cod fillets and thin sewing needles. In order to block the image from the surveillance cameras, the lines must be cut no matter what. In addition, even if the entire connection is restored with a remote control before committing the crime, there is still no time to dispose of the equipment, and all the equipment will eventually become evidence.

Captain Mu Ran has already stated that the entire line is undamaged.

Checking all the wiring in the fifteen-story building is not an easy task. Even if you just pull everything out, it’s a big project. Therefore, there’s no need to consider the possibility of the murderer replacing the wiring with a new line beforehand.

In other words, this method won’t work.

Then, there’s only one way left to change the image.

And the person who changed the image is the murderer!

It’s still puzzling, there are still a few parts that can’t be clearly explained. Is this a false appearance?

Wang Linfei left his apartment, preparing to have a few drinks at the bar downstairs. Because the recent case was very complicated, he might be able to learn from Mu Ran and detach himself from the tense case, which might help his thinking.

He went to the underground room across the street. Before going down the stairs, on the brass sign that read “Telee,” Wang Linfei pushed open the revolving door and entered.

The bartender, A Fang, who was wiping glasses, looked at Wang Linfei.

“Brother Linfei, welcome.”

“You seem to be free, A Fang.”

“Because of the bad economy.”

The once crowded bar now had only two regulars.

“Can I play a few racks? I haven’t played pool in a long time,” Wang Linfei said with interest.

“Please, the table is empty now,” A Fang said.

Wang Linfei nodded to the regulars as a greeting and walked to the pool table in front. After placing the nine balls at the foot spot, he picked up the cue hanging on the wall and chalked the tip.

Without saying anything, A Fang immediately added ice to a flat-bottomed, wide-mouthed glass and “Jim Beam” and placed it by the pool table.

Wang Linfei took a sip of the drink and broke with all his might.

The nine differently colored balls scattered in all directions with a powerful crash.

At first glance, they seemed to be rolling around in a chaotic state, but in reality, all the movements were based on the rules of geometry. Watching the colored balls roll, his confused thoughts seemed to be able to be cleared up quickly.

Returning to the starting point, he rethought the entire case, eliminating the impossible leads one by one. Now there was only one method left. But, this method still had many doubts. At least, according to his intuition, he didn’t think it was the right answer.

The nine colored balls were scattered on the table. The orange number five ball went into the pocket first, a good start. The position of the cue ball was also good. A Jing walked to the opposite side of the table, preparing to aim at the yellow number one ball.

So far, perhaps he had been too hasty, too eager to find the truth, and had overlooked something. If he put aside his preconceived notions and looked at the whole event from a distance, what would happen?

The yellow ball was near the corner pocket. He reduced the force of the cue ball and hit the opportunity ball. If, as planned, the cue ball would hit the colored ball into the pocket and stop in an ideal position.

While chalking the cue, Wang Linfei pondered.

Maybe the murderer was also using opportunity balls in a planned way.

In the case of Chairman Zhou Runmin’s murder, there was a very important characteristic, that the force of the impact was quite strong.

If the murderer committed the crime after planning everything, this point should also be in his plan.

Perhaps the slight force of impact was not accidental, but an inevitable result.

But, what did these represent? He couldn’t see it yet.

Wang Linfei swallowed a mouthful of wine, enjoying the burning sensation in his throat, and then aimed at other colored balls.

The blue number two ball went into the pocket effortlessly. However, the force of the cue ball was slightly off, stopping in a slightly awkward position. The next target was the red number three ball, but there were three other colored balls blocking it. After trying two or three empty shots, he felt that there was no way to aim smoothly.

The number three ball was like it was locked in a locked room.

Wang Linfei decided to try a jump shot.

He raised his left and right arms and slammed into the cue ball. The cue ball jumped up, over the obstacles in front. He saw out of the corner of his eye that one of the regulars even clapped and cheered, but unfortunately, it didn’t hit the number three ball, resulting in a foul.

If there was only one person, he could put the cue ball back in its original position. But since he was playing both roles, he should change the striker. Before the opponent fouled and changed hands, he could put the cue ball in any position he liked. Wang Linfei put the cue ball on the inside of the “locked room,” which was the ideal position to aim at the number three ball. Suddenly, Lu Yao’s voice flashed in his mind.

Thinking this way, Deller No. 3 can still move Chairman Zhou Runmin’s body, right? The murderer didn’t move the cue ball, but Chairman Zhou Runmin, who was the colored ball. Maybe this held the key to solving the mystery of the locked room.

Wang Linfei easily knocked in the number three and number four balls. The number five ball had been solved in the initial break. Next was the green number six ball. The invisible green ball was the hardest to find under the green pool table. Wang Linfei shook his head and knocked in the number six ball.

No matter how he thought about it, the murderer could only enter the locked room by using the blind spot of the surveillance cameras.

However… the location of the number seven red-purple ball was such that even if Wang Linfei lay on the pool table, it would not be easy to aim. He took the bridge from the wall and set up the cue. If there was a possibility of killing from a distance, the murderer would have to have a pair of arms as long as a bridge plus a cue. The only one who could play this role was probably a care robot.

Holding the end of the cue, he tapped it lightly, and the number seven ball disappeared. In this case, what was the cue ball, the murder weapon, used by the murderer?

What was the invisible hammer that killed Chairman Zhou Runmin?

The black number eight ball and the two-color number nine ball were lined up in front of the corner pocket.

The arrangement of these two balls was called dead.bo in English, which was the so-called “iron ball” state. As long as you hit the number eight lightly, you could kiss the number nine ball into the pocket. After easily clearing the table, just as he wanted to play another game, the phone in his front pocket rang. It was Lu Yao calling.

“Captain Wang, look at the information I sent you.”

“I was playing pool. Please wait a moment.”

A Jing opened his chat software. Lu Yao sent over what looked like cartoon illustrations. Like the cartoons in the newspaper, they were divided into four panels. Although Wang Linfei knew that Lu Yao was good at drawing, this illustration was of professional quality. It was hard to believe that it was Lu Yao’s work. Wang Linfei was shocked as he looked at the diagram… It was such a simple method? Why didn’t he notice it? Indeed, this method might be able to use Deller No. 3 to kill Chairman Zhou Runmin.

This method was not professional at all. He always tried to consider all the possibilities, but he still missed one, perhaps because his thoughts were not smooth enough, so one part was completely overlooked.

“…Hello, I’ve seen it. Lu Yao.”

“I think you finally understand the method of committing the crime. I got the inspiration by chance just now,” Lu Yao said excitedly.

How could there be such lucky things in the world!

“Amazing. Lu Yao!” Wang Linfei was filled with admiration.

“Thank you,” Lu Yao said, blushing.

“Although there are still some things I can’t figure out, such as where to operate Deller No. 3 from. However, I think this is still a very powerful assumption, but…”

“But?” Lu Yao was afraid that Wang Linfei would pour cold water on her.

“Whether it can actually be done, we still have to do an experiment to be sure.”

“Yes, I plan to call Mr. Zhou Junlong tomorrow and ask him to help with the experiment.”

“However, it will be meaningless if we don’t do this experiment with real objects at the crime scene.”

“I see…” Lu Yao said thoughtfully.

“That is to say, we can’t do the experiment without getting Mr. Liu Ziqi’s approval.”

“Even if we assume that Liu Ziqi is the real murderer, I don’t think he will refuse to help if we hide the details of the experiment. If he refuses, it will only make himself more suspicious. Besides, we can’t hide the evidence now,” Lu Yao said.

“Okay. I will arrange everything after noon tomorrow and try to conduct the experiment as soon as possible,” Wang Linfei said.

“Yes, definitely. I and Li Ke will both come to help you, Captain Wang.”

After hanging up the phone, Wang Linfei ordered another glass of single malt whiskey.

If the answer was as Lu Yao predicted after the mystery was revealed, then she had made great progress.

At this moment, Wang Linfei drank the whiskey in the glass in one gulp.

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