It turned out that after Lin Jia and Song Jin came to the interrogation room that Jia Wei had prepared for a long time, they did not immediately interrogate Wu Jian, but through the instruments they brought, they first tested the magnetic strength of the special tattoo on Wu Jian's wrist, as well as the material that presented the iron-red tattoo material.

At the same time, Lin Jia also read the transcript of the interrogation of Wu Jian brought back by Jia Wei.

Seeing Ling Zhan and Xun Jianguo walking in at the same time, Lin Jia greeted him and said, "Uncle Xun, Team Ling." Through testing, it can be determined that the tattoo material on Wu Jian's wrist is indeed a magnetic material, and it is a soft magnetic material called iron powder core. ”

Does that mean that after such a long time, the magnetism of the tattoo on Wu Jian's wrist is already very weak?"

Obviously, Ling Zhan knew some basic knowledge of magnetic materials.

"Yes, the remaining magnetism in the tattoo on Wu Jian's wrist is now minimal, but it can be magnetized again so that we can conduct further experiments. This is also what Song Jin is doing. ”

As soon as he said this, Song Jin walked over and said, "Forest Bureau, Team Ling, it has been magnetized." Because it has been too long, part of the tattoo material on Wu Jian's wrist has been lost, so now it can only be magnetized to a magnetic induction intensity of about 1.0T. ”

"As long as you can feel the change in the magnetic field emitted by the instruments we bring with us. ”

"It should be fine. ”

As he spoke, everyone leaned over together and witnessed the two young men brought by Lin Jia operating an electromagnetic wave generator the size of a small microwave oven, while Song Jin was in charge of making notes, and Jia Wei was in charge of asking Wu Jian how he felt.

"Do you feel it?"

"Yes, yes, but weaker. ”

"Turn the electromagnetic wave generator to maximum power. ”

Hearing Lin Jia's order, the two young men immediately agreed: "Yes, Forest Bureau." ”

"It's okay, it's very obvious. ”

Needless to say, Jia Wei, who was standing beside him, could see with the naked eye that as the two young people regularly adjusted the strength of the electromagnetic wave generator, the two iron-red dots on the special tattoo on Wu Jian's wrist were beating up and down.

"How strong is the signal you received on June 16th?"

"That's pretty much the way the vibration intensifies, but the frequency is not quite the same. ”

"What was the frequency?"

"It's almost once a second. ”

Hearing this, the two young men immediately operated the electromagnetic wave generator and turned it on every second.

"Yes, yes, that's it. There were a total of three jumps at that time. ”

"Isn't this just a human telegraph receiver?"

Jia Wei's words sound funny, but they say the essence of this kind of transmission of signals through electromagnetic induction—it is just a change from the ancient, outdated, and once great convenience for human beings to transmit information.

did not continue to interrogate Wu Jian, Lin Jia was most interested in whether the tattoo artist still had the remaining tattoo materials that Zeng Cheng had brought.

"I asked the tattoo artist at that time, and he said that although there was a little left at that time, it was taken away by Zeng Cheng again. It was only a tiny point attached to the needle, and because I was curious, I attached it to a magnet and kept it. But not long after, the magnet was taken by his son to play with without his knowledge, and in the end he didn't even know where to throw the magnet. ”

"Team Ling, have you searched Zeng Cheng's residence?"

Because Ling Zhan came late, he didn't know if he had searched before, so he shook his head and went to see Xun Jianguo.

"There were two searches before and after. Once before the arrest of Bai Yu, and once after the capture of Bai Yu. However, since our focus is on who bought Zeng Cheng and asked him to assassinate Yang Yutang through what means, we don't pay attention to anything else. ”

"Is there anyone else guarding the scene?"

"Yes, there are always police stations in the jurisdiction that send people to guard them. ”

"Is this okay, Team Ling, now I want to go back to Zeng Cheng's residence?"

"Yes, I just have time. ”

After speaking, Rong Liang, Zhao Zengyuan, and Qi Zhibin were left to continue to interrogate Xing Jun, and the others all went to Zeng Cheng's two residences in General City to conduct a third careful search overnight.

However, according to the tattoo artist's recollections, there was not much tattoo material left at that time. Even if Zeng Cheng didn't do any special treatment, it would be difficult to find it in a huge room. Therefore, eight or nine soldiers divided into two routes, searched for more than three hours, and by nine o'clock in the night, they almost turned Zeng Cheng's two residences upside down, and they didn't gain anything. So, in the end, I had to choose to give up.

"Lin Bureau, as Zeng Cheng, it is impossible for him to come into contact with that kind of tattoo with magnetic induction, in other words, it must be the person who paid to hire him to provide him with this method, including magnetic tattoo materials. Therefore, two possibilities cannot be ruled out, the remaining tattoo materials were either returned to the person who hired him by Zeng Cheng, or destroyed by Zeng Cheng at the behest of the person behind him. ”

"Under normal circumstances, that person would not meet Zeng Cheng, so how did they transmit that magnetic tattoo material?"

Xun Jianguo replied for Ling Zhan: "The first two times around Zeng Cheng's instructions on how to receive the instructions of the person who hired him, we can say that we investigated all of Zeng Cheng's contact information, including the express delivery, but there was no gain. ”

"Wouldn't it be another hacker to contact through the background of a certain website?" It can be heard that Lin Jia's words have obviously pointed to Yang Yuting again.

"We can't rule it out, but we haven't found any clues. ”

Because so much time has passed, it is impossible to capture the whereabouts of Zeng Cheng and his men during that time by the most stupid means of the nearby surveillance cameras. Therefore, Lin Jia immediately took people back to the National Security Bureau.

As Song Jin said on the phone, the magnetic induction tattoo found on Wu Jian's body did inspire Lin Jia. In particular, through the phenomenon that Zhou Wei's bank card fell into the hands of the person who ordered food for Yang Wenjing, who was raped and killed, it was basically determined that the person who hired Zeng Cheng was Yang Yuting, and Lin Jia paid more attention to it.

Regarding Yang Yuting's abnormal behavior of going to the Labor Park for morning exercises for a few mornings every three or five days, Lin Jia is confident that his judgment will not be wrong, that is, Yang Yuting, who has already gone through the exit procedures, is using this unpredictable way to confuse, or paralyze national security and public security, so as to create conditions for the next contact with the deeply hidden line.

As for whether he will use this kind of magic to put it bluntly - it is almost a copy of the long-outdated telegram, but it is precisely because of the ancient and easily overlooked magnetic induction method to contact his upline, Lin Jia is not sure. But with one more option, it's always a good idea. Therefore, as soon as he returned to the bureau, Lin Jia began to prepare. The first thing to do is to choose a suitable magnetic sensing instrument – not too large, but also very sensitive and not easily detected by other instruments.

It didn't take much brains, Lin Jia thought of the compass that is now ubiquitous in a flash. Whether it's a watch, many mobile phones have similar functions.

However, it is not difficult to detect the electromagnetic wave anomaly in the surrounding environment in this way, the difficulty is that if the other party really chooses the electromagnetic induction method, and it is used to transmit information, then it is impossible to record the wavelength and frequency of electromagnetic waves and other parameters by relying on the compass, and there is no way to decipher the content of the information.

However, this is not difficult to help but be the National Security Agency, which specializes in intelligence gathering. When Lin Jia reported the situation, only two days later, he received a small and delicate special device similar to a watch, which could be worn on the wrist. It can not only detect the abnormal fluctuation of electromagnetic waves within 500 meters around you, but also accurately record the wavelength, waveform, frequency and other parameters of electromagnetic waves.