Proof by Contradiction

  I don't understand why the car is Du Xiangyuan's biggest weakness again. Didn't the police already search for his vehicle entry and exit records through the surveillance equipment on the road section and rule him out as a suspect?

  "But Gao Cheng said, 'You all haven't grasped the key point. At both crime scenes, there were no suspicious vehicles present. I inferred two possibilities with a higher probability, but they are not absolute. Precisely this Du Xiangyuan satisfied another possibility outside of probability, if his testimony is that neither he nor the vehicle left the city, it's more believable. This is reverse logical reasoning.'"

  I roughly understood his meaning, the testimonies of the three witnesses were different, but at the same time they all satisfied that there was no vehicle at the scene of the crime. So no matter how brilliant your testimony is, it can't rule out suspicion.

  "And then how did you further confirm it?" With just this point alone, Gao Cheng would not lock onto Du Xiangyuan.

  "Method of probabilistic exclusion."

  I didn't quite understand, and my eyes were filled with suspicion. Gaotai patiently explained: "Three people, excluding two, the remaining one is the most likely. During the first interrogation, Qin Yali's eyes darted back and forth, Ma Tuo was calm, these are all related to their own temperament; in comparison, Du Xiangyuan's reaction was the most interesting, restrained, suppressed, sad, these contradictory emotions were presented simultaneously on one face, usually this kind of person has the most psychological characteristics."

  At this point, I couldn't help but sigh inwardly, all I could say was that Du Xiangyuan had bad luck and ran into Gao Cheng.

  It's not the first time I've noticed that Gao Cheng's eyes gleam with intensity when he's analyzing something, which is completely at odds with his usual languid demeanor. I pause for a moment and follow his train of thought: "So you later arranged to have the three of them interrogated separately? Was it a psychological tactic?"

  Gao Cheng shook his head: "They're not at the level of playing psychological warfare yet. If we find a security guard to test them, they'll reveal their true nature."

  My heart skipped a beat as I suddenly remembered a detail and asked in shock, "Was that person the villa's security guard?" When Qin Ya Li was taken out of the interrogation room by Xu Jiang Lun to another screen, there was a man in his late 40s being questioned near the corridor. At that time, I took a closer look and noticed that Qin Ya Li hesitated for a moment when passing by, while Du Xiang Yuan quickly glanced over. Ma Tao was left in the interrogation room and didn't have this scene. Soon my attention was drawn to what happened next, and I forgot about this detail.

  Once the key is pressed, many things in the mind begin to clear up. This case actually has many doubts, first of all, there are no suspicious vehicles entering and leaving, which has been explained just now; secondly, it's about surveillance.

  The current regional surveillance is all over, especially in the villa area, and security measures will be strengthened. However, a few nights ago, there was a storm, and both the building where Wu Yan lived and the villa area where Yu Xiuping lived had damaged surveillance cameras, making those two areas blind spots. The camera inside the elevator on Wu Yan's floor has been broken for unknown reasons and hasn't been repaired. In other words, the surveillance became a mere decoration and also created favorable conditions for the murderer to commit the crime.

  When many coincidences come together, they become intentional.

  But I still can't figure it out. Judging from the behavior of the two people passing by that table, shouldn't Qin Yali know the security guard and have been to the villa before, while Du Xiangyuan is innocent?

  It's as if he knew what I was thinking, Gao Cheng said lightly: "Stop those subjective notions in your brain, it's all about seeing through the phenomenon to the essence. The fact is that Qin Yali's behavior belongs to the subconscious operation, while Du Xiangyuan's limbs are controlled by brain cells, this arrangement is not a test of who is more calm, but to let the person with a ghost in his heart show his true colors."

  "So, at that time you already had a conclusion? Why still need to make Qin Ya Li undergo the will test?"

  Gao Cheng leaned against the back of his wheelchair, half-closing his eyes and said, "If you're going to flay someone, don't leave anything out."