Shen Cheng and I caught the attention of one resident's remarks and told us that Luo Danan and Chen Zhaodi's family, who were Catholic Churchists, would go to a nearby church every week to pray.

Shen Cheng stood up suddenly, he immediately asked where the church was, and judging from the expression on Shen Cheng's face, he found an important clue. The resident immediately told Shen Cheng where the church was located, Shen Cheng looked at his watch, it was very late, he took a deep breath and sat back in his chair.

"Do you want to go to that church?" I asked.

Shen Cheng looked at me and told me truthfully, "Yes." ”

When the inquiry was over, Shen Cheng and I went back to the office, Shen Cheng picked up the pen and wrote something on the paper, and then he threw the blank paper to me. There are several keywords written on the white paper, all of which are related to the case: the church, the greedy, and the thirteenth floor.

"What do you mean?" I looked at it for a while, but I didn't understand it.

"In Catholicism, greed is one of the felonies, and thirteen, in the eyes of the West, is also a very ominous and disgusting number." Shen Cheng explained to me.

When Shen Cheng said this, I understood, he thought that the death of this family of three had something to do with the church.

"Religious killing?" I asked rhetorically.

Shen Cheng shook his head: "Not necessarily, but it may be related, so I want to investigate." ”

At this time, someone from the criminal department came, and they brought us good news. Based on measurements of the construction site, and based on the weight of the stone and other data, they calculated the thrust and angle at which the large rock would land at a given location. After the results were calculated, the people in the criminal department simulated another experiment using the same scenario.

After several tests, police cameras recorded the trajectory of the large rock falling downward.

As he spoke, the staff of the criminal department played the videotape.

The distance was relatively long, but that didn't prevent us from seeing the big rocks falling downward. The video has been processed by the Criminal Division, and the video has been slowed down after the large rock has been pushed out of the edge of the thirteen-story building. The boulder slowly fell downward, and after treatment, the trajectory of the boulder was marked by a red line.

The moment the boulder fell to the ground, the complete trajectory map appeared, exactly as I had inferred, and the boulder appeared as an inconspicuous parabola.

"We tried a lot and finally got the big rock to land in the designated spot." Said the officer of the Criminal Division.

The officers of the Criminal Division told us about the difficulties they had in the process of calculation and experimentation. Needless to say, in order to obtain very precise data, the criminal officers took various tape measures and measuring tools, and many people cooperated, so that the required data was gathered. When calculating, several criminal officers perform calculations at the same time, and they have to consider many factors, such as the friction of the stone on the ground, and the resistance of the boulder during the descent.

After hours of manual calculations and repeated verification, they finally came up with the required thrust and angle. However, the difficulties are much more than that, because it is all on paper. When it comes to actually doing it, they encounter even greater obstacles.

The biggest problem, first of all, is how does a person know how much thrust he is using when pushing a large rock. Is it pushed by a precise pushing machine? It is unlikely, a machine that can push such a heavy stone can be moved by a person, but it is more difficult to move it to a place thirteen stories high.

Moreover, there were no traces of pushing the machine to stop at the site on the thirteenth floor. Therefore, the murderer may have some measuring tools to assist him when pushing the big rock, but he pushed the big stone with his own hands.

With this in mind, the officers of the criminal department also used their hands to push the test by hand, first estimating how much force they would have to use, and then pushing the large stone at a fixed angle. But there was an error in people's estimates, so several times down, the stone was missed. The last time, I don't know if it was luck, the big stone finally landed in the designated position.

After reading the process and report of the test, Shen Cheng nodded: "It is possible in theory, and it is also possible in practice, that is to say, the murderer not only understands physics, but is also a genius in physics." ”

I do not deny Shen Cheng's inference that the murderer certainly did not carry out the measurement and data extraction of the scene as blatantly and fanfare as the police, he could only measure by visual inspection or secretly when no one was there at night, but in this case, he still obtained very accurate data.

People from the criminal department told us that it is very difficult to practice, which requires absolute accuracy of the data when making theoretical calculations. The murderer hit Luo Danan, proving that he did it. Not only did he get accurate data, but he also used accurate force when pushing the big rocks.

If a person wants to use accurate force in a single movement, he must repeatedly perform mechanical training, just as in military training, they are required to produce the same pressure with each step and the same height with each foot lift, within the negligible margin of error.

The murderer must have put a lot of effort into pushing the big rock that time.

Through simulation, we can roughly deduce the process of the murderer in the first murder case, and as for the process of the second murderer, due to insufficient evidence and clues, we have no way to infer it.

Shen Cheng and I made an appointment, and we were going to go to the church early the next morning. Shen Cheng's suspicion was not unreasonable, if it was really a religious killing, the deceased died on the thirteenth floor and could be explained. To be honest, such a heavy stone, as long as it is placed on the fifth or sixth floor and pushed down, it is enough to put people to death, and if it is placed too high, it is easy to produce errors in the falling position.

But the murderer still chose the thirteenth floor, whether it was accidental or deliberate. If it is deliberate, the number thirteen can indeed be associated with religion, because in that sect, the number is ominous. In many floors in the West, there is no thirteenth floor, and when it is marked, it jumps directly from twelve to fourteen.

The motive for the murder seems to be explained if it is a religious homicide, greed is a felony of that religion, and if it is an extremist religious person, it is perfectly reasonable that the family could be killed simply because they are so greedy.

Before going to the police station, I asked Shen Cheng about the progress of the investigation of the killer organization.

Shen Cheng glanced at me: "You don't have to worry about this, you better put all your mind on this case, don't you think, you're about to lose?" ”

Shen Cheng and I looked at each other, and so far, Shen Cheng has predicted a lot of things that I didn't expect, such as Luo Danan's bending posture before he died, the murderer will kill Chen Zhaodi, and so on. Compared to all the investigators I've seen before, Shen Cheng is not only quick to think, but also accurate.

Me: "Until the last minute, there's no way to be sure. ”

Shen Cheng smiled: "Dead ducks have hard mouths." ”

Me: "So, is there a whereabouts for Wang Xin?" ”

Shen Cheng: "No. ”

Shen Cheng didn't seem to want to mention the killer organization, so he got up and walked out of the police station directly. The car quickly disappeared from my view.

Shen Nuo had already returned, she was lingering at the door of the hotel, and when she saw me, she seemed to have something to say.

"What's wrong?" I asked.

Shen Nuo did not answer.

"Did something happen, where the hell did you go last night?" I was a little anxious, because Shen Nuo's face was very ugly, and his lips were white and there was no blood at all.

Shen Nuo suddenly sighed, and she looked at me: "Tell you a good news." ”

I was slightly stunned, Shen Nuo's expression was very serious, I just thought she would tell me bad news, but I didn't expect that she really brought me good news: Xu Yi was safe and sound, and appeared in a coastal city yesterday.

The heart that had been suppressed for a long time finally relaxed, I knew that Shen Nuo would not lie to me, she would only not tell me, but what she said was absolutely true.

"Now, where is she now, and is there any news of her?" I smiled rarely, no matter what purpose Xu Yi left me, I didn't want anything to happen to her.

However, when I asked this, I saw tears flickering in the corners of Shen Nuo's eyes......