The villain is trapped in the system and begs me to let him out [Moriarty who worries about the coun

"Interesting, how did this happen..." William suddenly narrowed his eyes, as if he had noticed something abnormal, "I see, did you use the camera function?"

Du Ruoying lowered her head in frustration: "You actually figured it out, so I don't need to say more."

"No, I just noticed a subtle change in the color of the screen. It seems that I can vaguely see a little reflection. But I don't understand how this technique works. I need Xiaoying to explain it from beginning to end."

"Okay then," she brought the laptop in front of him, "it's actually like this. The murderer first took a picture of your lock screen desktop with his own mobile phone-I just checked the question about moiré, although You may not know, but when the refresh rate of a display screen is lower than the shutter speed of the mobile phone, the captured picture will have interference ripples, that is, moiré, and this problem can be solved by reducing the shutter speed.

"Then use a computer software——Photoshop, adjust the perspective and color scale like this, erase the 10 at 11:0, copy a 1 from other numbers, put it in this empty space, and create a false time interface gone."

Watching Du Ruoying's smooth demonstration operation, William fell into thinking: "Is the technical threshold of this method really lower than that of 'violent lock breaking'? It seems to me that not everyone can easily use it." way."

"It's definitely much lower," Du Ruoying vowed, "As long as you are a person who has studied design, this operation is not a problem at all."

"However, the reason why this 0 can be easily erased is just because my lock screen desktop is relatively simple, right? Wouldn't it be very troublesome if I encountered a complicated desktop, such as the rose window pattern of a church?"

"It's okay, it just takes a little longer. In fact, no matter how complicated the pattern is, it should be done within half an hour-at least my processing speed is like this. Besides, I will give you It’s just a glance, even if there are flaws in the processing, you won’t find it in time.”

"That's true."

"In the end, the murderer took a picture of this false interface with your mobile phone—of course, I think he should be more careful than me in taking pictures, so as not to leave obvious errors such as reflections. After taking the picture, use the built-in mobile phone The editing function adjusts the perspective and tone, like this, and then puts it directly back in your pocket, wakes you up, and takes the phone away from your face before it has had time to turn off the screen, so you can see the time. Finally, Before your screen locks again, he permanently deletes the photo, and that's it.

"However, in order to leave no trace of the deleted photo, there is another thing to do." She said, "Actually, I thought the murderer would dispose of your phone. After all, this method is easy to leave traces. But I just discovered that the other party seems to have used another method - he used your mobile phone to take a lot of meaningless photos and videos in advance and deleted them all, and repeated the operation many times until the space is full, and when he deletes new photos next time, It will not be put into the 'Recently Deleted', so that no trace will be left—of course, this should be only superficial. If you give the phone to Bai Qirun, he may have a way to restore that photo come out."

"So that's what it is. It's really a trick that took so much effort." William nodded submissively.

"Then it's your turn to talk about how the technique of the double secret room was realized."

"Before that, in order to confirm my conjecture, I need to ask classmate Xiaoying a few questions. First, have you ever tasted the rusty iron door?"

"Huh?!" Du Ruoying was obviously confused.

"Sure enough, it doesn't seem to be." He shook his head pretending to regret.

"...Why should I taste that? It's rust, 100% rust. Don't all rusts in the world have the same taste? Can I still taste chocolate?" She said speechlessly.

Hearing this, William couldn't help chuckling: "Student Xiaoying, you still have to learn from Charideau in this regard. As a detective, you must be as sharp as a hound when investigating the scene , otherwise you will miss a lot of key clues. If it is Xia Li, I think he will definitely try the rust one."

"...Can you stop being a joke and get straight to the point?"

"Okay, give me your phone, and let's take a closer look at the photos of the scene." William stretched out his hand, "Actually, I think it's not hard to imagine with Xiaoying's knowledge base—first of all, the secret room of the air-raid shelter. Have you noticed any problems with the rusted state of the iron door and iron lock?"

"The whole iron gate is in a mess of rust. Before we broke in, the rust spread across the iron lock and bolt, and some fragments were even coherent and complete," Du Ruoying replied, "This means that the lock has not been opened for a long time. gone."

"Why is it that the rust is coherent and complete, so it must have been untouched for a long time?" William coaxed, "You see, whether it is the shady side or the sunny side, the degree of rust is so uniform in each position, which is not what natural rust can do— —”

"Ah..." Du Ruoying's eyes widened suddenly, "It's a salt spray test!"

"That's right, in a humid environment with a higher temperature, spraying a solution of sodium chloride, copper chloride and acetic acid can cause serious corrosion and rust of brand-new ironware overnight, and finally go up A little dust can make people think that the door has not been opened for a long time."

"No wonder you asked me about the smell of iron filings. If the murderer really used this method, it should taste salty." She suddenly realized.

"Otherwise, do you think I'm looking for faults maliciously?" He glanced at her helplessly, "Next is the second secret room, and before that, I also need to confirm a question with you—did you try How about sticking your hand in the mud and feeling it?"

...? ! !

But after learning the lesson from the previous time, Du Ruoying didn't dare to talk back rashly this time. She shook her head obediently and said sincerely, "What is this for proving?"

"Verify the temperature." William said, "Look at the series of footprints in the photo, do you find anything wrong?"

Du Ruoying stared at the screen for a moment, and suddenly realized: "On the way back, my footprints... were actually deeper than Su Xiaochuan's. This is impossible! He was still carrying you behind his back!"

William, however, just smiled at her silently.

"You just said to verify the temperature..." Du Ruoying's brain began to run rapidly, "I know! It's liquid nitrogen! The murderer carried a tank of liquid nitrogen on his back, and walked forward while spraying, freezing parts of the silt hard, and he was able to Create a path that leaves no footprints.

"It just so happens that it is midsummer, and the torches and candles are burning all night in the air-raid shelter, which makes the surrounding air temperature very high, so after the morning, the part of the frozen silt will naturally soften again. But it was softened at that time. Su Xiaochuan just stepped on that road when he came back, so his footprints are shallower than mine. If you put your fingers into the deep mud to feel it, you will find that the temperature in that place is higher than that in other places. lower."

"As expected of classmate Xiaoying, she really knows a little bit about it." William applauded calmly.

"However," Du Ruoying was not happy about this rare compliment for the time being, "Although the secret room technique and the alibi trick have been solved, it is still unknown who did it. You have a clue about this Is it?"

"not yet."

"Really?" she asked suspiciously.

"Well, really."

"Looks like I need to collect some more information," Du Ruoying stood up, "Well, I'll go and return the computer first, and see if I can ask about Ah Cheng—didn't they say that here a few years ago? Has there been a similar case, I feel this will be a breakthrough."

However, things did not go as smoothly as she had imagined.

When returning the computer, she tried to inquire about the situation from Keya, but when the other party heard Ah Cheng's name, she immediately excused that she was busy with other things, and then left.Then Du Ruoying went to the kitchen to ask Aunt Zhang about it, but she didn't know anything about what happened before Aunt Zhang came here.As for Su Xiaochuan, as an outsider, he didn't even know what to ask.

Du Ruoying had no choice but to go to the west hall to look for Karl, but she was directly refused to answer. Wu Yeling was the most indifferent, not only did not open the door, she didn't even answer a word. If she hadn't vaguely heard the sound of water in his room, she would have almost thought him not there.

The only person who was willing to tell her the details was Wen Qinglan, but she only said, "Ah Cheng's full name is Zhang Zecheng, and he used to be the design assistant here", but Carl who heard the news stopped him.

Du Ruoying felt deeply frustrated after running around for a long time but couldn't ask any questions.Just as she was about to leave the gate of the west hall, the commotion at the gate of Wu Yeling's room caught her attention.

She ran over to take a look and found that William was also in the crowd.

"what happened?"

"It's like this," Aunt Zhang explained to her, "Mr. William's landline seems to have received a distress call from Mr. Wu Yeling just now. Everyone came over to check, but found that the door of Mr. Wu's room was locked. Shouldn't."

In this way, there was no answer when she knocked on the door just now.

Could it be that--

"Where's the spare key for this room?" Du Ruoying asked.

"Early in the morning, Mr. Wu said he couldn't find the original key, so he borrowed the spare key, so I don't have the key now."

"Then we can only hit the door," Carl said, frowning tightly, "Xiaochuan, come with me."

The moment the door was knocked open, the first thing that caught the eye was the mist that diffused from the bathroom.Through the white mist, everyone vaguely saw a figure sitting in the corner of the bathroom—it was Wu Yeling, with a dagger stuck in his heart, and many stab wounds on other parts of his body, with different depths, and the wounds were crisp and sharp. They were all stabbed after the victim lost the ability to resist, full of abuse.

The shower head in the bathtub was still pouring hot water, overflowing all over the floor, mixed with streaks of blood, and pouring into the sink continuously.

There is no doubt that this is the second homicide.

Ironically, the spare key of the guest room was quietly lying in another corner of the bathroom at this moment, and the so-called "original key that could not be found" was placed in the most conspicuous position of the TV cabinet.

Du Ruoying's eyes slowly turned to the doors and windows on the balcony, as she expected, they were all locked behind -

Another secret room.

Was the door locked from the outside with scotch tape?No, it's impossible.This lock type is particularly complicated and delicate, and can only be locked by hand from the inside, or locked with a key from the outside.

So could it be that the key was pulled in by a fishing line trick?I'm afraid that's not possible either.Although the width of the bottom door slit is just enough to allow the key to pass through, no matter whether it is this empty bathroom corner or the TV cabinet, there is no necessary fulcrum for the fishing line to form a turning point.

"How likely is it that a key for this guest room will be secretly assigned in advance?" Du Ruoying looked at the delicate and complicated tooth shape on the key, feeling faintly uncomfortable in her heart.

"I don't think there is such a possibility." Keya said worriedly, "All the door locks in the villa are custom-made by a company in Germany. To get the keys, you have to go to Germany with the certificate of purchase and identification. , it cannot be matched in China. But the purchase certificate has been kept with me, and no one has touched it, and we have never been to Germany again.”

While listening to Keya's words, Du Ruoying approached Wu Yeling's body cautiously. Looking closely at the degree of coagulation of blood from these wounds, she could tell that the victim's death time would not exceed an hour.She also noticed that his right hand was clenched loosely, as if he was hiding something, and when he opened it, it was a strand of wet bloody gauze.

At the same time, William secretly clutched the bloody gauze on his right hand.