Zhang Yang pointed to the place in front of them: "This is where the explosion happened that day." Wu Dezhi nodded. The scene had been cleaned up, and there was no trace of the explosion on the surface.

In terms of describing the scene, Geng Zhichao was obviously more professional. He explained the details of the day to Wu Dezhi, and accurately pointed out the location of the vehicle at that time and the range of the explosion.

Wu Dezhi carefully inspected the site, but found some clues in places that were difficult to clean.

Geng Zhichao said to Zhang Yang: "He used to be the best bomb disposal expert in Guoan..." After saying that, he paused again and said: "It has always been."

Zhang Yang expressed satisfaction with Geng Zhichao's additional explanation, and he whispered: "The outcome of such an excellent expert is not good."

Geng Zhichao sighed, it was inconvenient for him to comment on the past.

Wu Dezhi returned to their side after inspecting the scene and said to Geng Zhichao: "Is the wreckage of the vehicle still there?"

Geng Zhichao nodded and said, "Caoqiao Parking Lot."

Wu Dezhi said: "Let's go and have a look now."

Caoqiao parking lot is not far away. When you arrive at the parking lot, Wu Dezhi went to check the wreckage alone.

Geng Zhichao took out a cigarette, took out one and handed it to Zhang Yang. Zhang Yang waved his hand and said, "No."

Geng Zhichao said: "The murder of Director Xing has attracted great attention from the superiors. A special task force was set up as soon as possible and asked us to solve the case within a time limit. The pressure we are under is also very great."

Zhang Yang said: "Some people always start to act after they happen. What did they do before? So many things happened before, can't they be alerted?"

Geng Zhichao sighed and said, "Our opponent is just too cunning."

Wu Dezhi inspected the wreckage next to the vehicle for half an hour. He did not miss any details. After he completed all the survey, he quickly came to the conclusion: "Guan Cheng! It is Guan Cheng's usual technique."

Geng Zhichao said: "How can you conclude that it is Guan Cheng?"

Wu Dezhi said: "Guan Cheng likes to use liquid explosives, and this kind of car bomb itself is what he is best at. He connects the bomb's detonation device to the car circuit. I have worked with him, and I am very familiar with his techniques."

Geng Zhichao said: "If I remember correctly, you were injured in Dongjiang back then, and he was the one who took action!"

When Wu Dezhi heard Geng Zhichao mention this, he frowned. He used his teeth to take off his gloves and whispered: "I have done what you asked me to do. Can I leave now, right?"

Geng Zhichao said: "Can you tell me some other situations about Guan Cheng?"

Wu Dezhi said: "I haven't seen him for a long time. If I could find him, I would stuff a bomb into his crotch with my own hands."

Geng Zhichao said: "Can you join our task force if you Dezhi?"

Wu Dezhi shook his head and said, "I'm sorry, I will never go back again. I am a disabled person and it's your own business to arrest people." After that, he turned around and left.

Zhang Yang followed his footsteps and got into his car with Wu Dezhi.

Zhang Yang drove away from the scene and said, "Why do I feel that you are very annoyed by Geng Zhichao?"

Wu Dezhi smiled indifferently and said, "It's not like it, and of course it's not annoying. I'm not familiar with him at all. You don't understand the situation within the organization. They came to me not only to ask me for help, but also because they doubted me."

Zhang Yang said in surprise: "Suspicious of you? Why do they doubt you?"

Wu Dezhi said: "I am familiar with their methods of doing things. When Director Xing was killed, the first thing they locked in was a few people who had been engaged in blasting majors in Guoan. Among them, Guan Cheng and I have the highest level of business. They would not have thought that Guan Cheng would let me do it, mainly to conduct investigations."

Zhang Yang said: "This group of people is really useless. Why don't you catch Guan Cheng if you have so much time?"

Wu Dezhi said: "If you believe me, it may not be possible for others to believe it. It is normal for investigation. Guan Cheng is very cunning and talented in explosions, but his style is obvious. He never considers the consequences of the explosion, or whether it will affect the innocent. As long as he can get rid of the target, he will not care about anything else."

Zhang Yang said: "He should be a madman."

Wu Dezhi nodded and said, "Even a genius will leave clues. The bomb he used to blow Director Xing to kill is homemade and not a finished product of arms, so it is difficult to trace the source."

Zhang Yang said: "Doesn't that mean it's difficult for us to catch him?"

Wu Dezhi said: "The source of the bomb cannot be found, but we can start with the material he used to make the bomb. The material he used is called triacetone triperoxide, referred to as TATP, which is synthesized from acetone and hydrogen peroxide at low temperature under a catalyst."

Official Zhang did not understand these professional things, what he was concerned about was how to find Guan Cheng.

Wu Dezhi said: "The two materials of acetone and hydrogen peroxide are very common and easy to find, but if they are difficult to buy in regular stores, because there will be registrations, there are usually two simplest ways to obtain these two materials, one is the school and the other is the hospital. Relatively speaking, the latter is less difficult. We can investigate Guan Cheng's social relations network and select people who are related to him and those who work in these two aspects, so we may find clues from it."

Zhang Yang said: "You didn't say these words to them just now."

Wu Dezhi said: "I don't believe them. There have been so many things inside recently, and it's hard to say who is trustworthy. They can doubt me, and I can doubt them."

Zhang Yang said: "Let's go, I can only ask the public security system for help in this matter."

Yu Qianghua was a little surprised by Zhang Yang's visit. After hearing his purpose, he further verified the principle of not entering the Three Treasures Palace without any trouble. In the previous Bagua Sect, Yu Qianghua always felt that he was indebted to Zhang Yang. Yu Qianghua agreed to Zhang Yang's request to investigate Guan Cheng's social relations.

Guan Cheng has been away from Guoan for four years. Even Yu Qianghua can do nothing about the archives and information of Guoan during that period. However, they still found some clues. Among Yu Qianghua's relatives, two were engaged in medical care and one was engaged in education. Among them, Guan Cheng's ex-wife Yang Yue'e worked in Xijing District People's Hospital, and her position was the pharmacy department.
Chapter completed!