"The top-level inspection didn't find any suspicion of murder on the security guards, right?" Xu Tian asked.

"We tested this morning, and neither suspect was suspected, at least through the results of testing fingerprints, shoe prints and other traces, they were not found to be suspected of committing the crime." The police said.

"So there are no traces of anyone else detected at the two crime scenes?" Xu Tian asked.

"No, not even the traces of being wiped have been detected, and the two victims are as if they were killed by ghosts." The police said.

"The victim on the top floor died of poisoning, although it is a little difficult to detect where the victim took the poison, but the victim should be able to detect traces by locking the victim in the heating valve on the top floor, is there no fingerprint on the iron door of the heating valve other than the security guard and the victim? Didn't even detect any traces of the iron door that had been tested? Xu Tian asked.

"That's right, but even if no other people's fingerprints were detected, and no traces of wiping were detected on the iron door, there are still ways to close the iron door, for example, the murderer can take an iron rod or a wooden stick or something like that to push the iron door up, because the iron door only has a door lock, there are traces of security guards patrolling and opening it every day, and there are no traces of anyone in other places." The police said.

"That makes sense, but what about the scene of the crime? Apart from the occupants, security guards and victims, no trace of anyone else was detected? You can't just kill the victim by the murderer standing outside the door! Xu Tian said.

"So we brought you here, Officer Chen explained, and asked you to help us if we have a problem." The police said.

Xu Tian glanced at the police very reluctantly, in the case of no clues, Xu Tian had no choice, after all, Xu Tian also had to find clues to solve the case, at least there should be some clues that conform to realistic logic.

But this also shows a problem, the murderer is very smart and does things very neatly, leaving no traces at the crime scene, making the crime scene look so natural.

In Xu Tian's cognition, few cases will be done so cleanly, even detectives rarely write stories without any clues, but this kind of thing Xu Tian has encountered not once or twice.

Although the case in front of him seemed to be perfectly done, Xu Tian did not believe that the murderer would float in like a ghost and cover the victim.

Thinking of this, Xu Tian suddenly had an idea in his heart, just now Xu Tian thought that the murderer could not float like a ghost, and this question seemed to wake up Xu Tian.

Maybe it was really like that, the murderer did not step on the ground and walked into the crime scene, because the crime scene was open, and the murderer did not arrange the crime scene as a secret room, if the murderer felt that he had committed the crime perfectly, then why did the murderer not close the door after leaving the crime scene? If the door is closed, the case looks even more mysterious.

The murderer didn't do that, Xu Tian knew very well that the murderer didn't do it, it must be reasonable, was there a reason why the door couldn't be closed? Or does the victim have a reason why someone else has to find out quickly?

"There it is!" Xu Tian suddenly shouted. "Are there any rules for security patrols here? Are they all patrolling on time? ”

"That's right, this is the daily work of the security guards, and the patrols are all on time, and now the property of the person in charge is basically arranged for the security guards to work in this way." The police said.

"That is to say, the murderer deliberately let the victim's body be discovered by the patrolling security guards, the murderer knows the patrol security guards of this apartment very well, the murderer knows that the security guards will determine whether there is anyone in the room after seeing the open door, and when the security guard does not hear no speech in the open room, he will generally knock on the door twice and ask, if no one in the room answers, then the security guard will help the occupant close the door." Xu Tian said.

"That's the logic, but what are you trying to say?" The policeman asked curiously.

"I'm making a hypothesis about whether the killer wanted the security guard to close the door or the security guard to see the body in the room." Xu Tian said.

"Huh? What kind of logic do you have? The police asked.

"Obviously, no matter from which point of view, the murderer wants the security guard to find the victim, but I think this logic is a bit unreasonable, if the murderer wants to hide his whereabouts, it must be that the victim is found as late as possible, even if the security guard is not allowed to find the victim's body in advance, and when the time comes to get off work, the resident will find the victim's body when he returns home, so this point makes some sense." Xu Tian said.

"It seems like that, but does it have anything to do with the case?" The police officer asked.

"What the murderer did is reasonable, but it doesn't mean that everything the murderer arranged is according to his plan, it is possible that the murderer wanted to close the door and leave the room at that time, but at that time, it is possible that the other residents on the third floor came out of the house, or came back from outside, then the murderer may hide back in the room. But the killer couldn't touch the door, so he didn't close the door, and when the other residents outside returned to their homes or left their homes, the killer walked out. Xu Tian said.

"But I still haven't figured out what this has to do with the case." The police said.

"You go and investigate whether there are any residents on the third floor who returned to their homes or left their homes during the crime, and just check the monitoring of the elevator." Xu Tian said.

As Xu Tian said, during the period of the crime, there was indeed a third-floor resident who left the house, but the resident who left the house was far away from the crime scene, and the head of the household who left did not pass by the crime scene.

"That's right, the murderer did not have a strong psychological quality, the murderer must have been very panicked at that time, and the murderer was likely to forget the most important thing in the panic, I speculate that the murderer forgot to close the door, which led to the victim's body being immediately discovered by the patrolling security guards." Xu Tian said.

"You're saying that the killer was going to close the door with something like a wooden stick or an iron bar?" The police officer asked.

"There is this possibility, because there are no clues left at the crime scene, which means that the murderer may have planned to make the crime scene a closed room murder case at the beginning, but the murderer did not do it in the end, which means that it is possible that the murderer changed his mind temporarily, but do you think the murderer would do this? If the body is found by others in advance, not only the security guards, but other residents may also take a look inside when passing by the scene of the crime, although the current neighbors may not know each other, but it is also possible for the neighbors to go in and take a look when they see someone falling in the house, and the murderer will not take the risk of the neighbors sitting idly by. Xu Tian said.