To thoroughly investigate Li Yang's case, the first step is to return to the crime scene.
Fortunately, the scene was well-preserved, considering the victim was an auxiliary staff member of the training institute.
"This shoeprint is the same model as Li Yang's leather shoes, and the sole pattern is identical," Lü Qingqing said, pointing to the footprint on the gray surface. "But this only proves that this footprint was left by Li Yang's leather shoes."
Lü Qingqing's point was clear: the footprint was made by Li Yang's shoes, but not necessarily by Li Yang himself.
Mo Yun had already been examined by Hu Jia and others. One stab wound to the abdomen and one to the chest.
Each stab was fatal.
Clearly, the killer was determined to ensure Mo Yun did not survive.
The case file for Li Yang's murder states that Ma Cong saw Li Yang climbing over the wall at 9:30 PM. Li Yang then walked back to his dormitory and, about ten minutes later, passed Mo Yun's room. He saw the door ajar and discovered Mo Yun's body.
This establishes that Mo Yun was dead by 9:40 PM.
However, Lü Qingqing clearly remembered seeing Mo Yun come out to fetch water at 8:45 AM.
This means Mo Yun was killed between 8:45 AM and 9:40 AM.
This presents a puzzle. From 8:30 AM, Lü Qingqing was guarding Mo Yun's door. They did not leave until 9:20 AM, and during that time, no one entered or exited Mo Yun's room.
If the murder occurred between 9:20 AM (when Li Yang left the institute) and 9:40 AM (when Li Yang climbed the wall), it seems theoretically impossible. In just twenty minutes, the killer would have had to commit the murder, stage the scene, and leave Li Yang's footprints, which is incredibly tight on time.
Most importantly, a witness confirms seeing Mo Yun at 9:30 PM.
Therefore, the ten-minute window is even more impossible.
Is it possible that Ma Cong lied, and the victim was actually killed after 9:40 PM?
To address this question, Hu Jia and Lü Qingqing conducted an experiment.
It takes about 15 minutes from Tongyuanmen Police Station to the training institute, and half an hour for a round trip. This is the time required for Ma Cong to report the crime and for the police to arrive.
From the training institute to Li Yang's home takes 30 minutes. This is the travel time for the police to arrest Li Yang after confirming he was the murderer.
Li Yang was arrested at 11:10 PM.
This means the travel time alone accounts for an hour. There was only a 30-minute gap in between. This gap was just enough for the police to process the scene; any further activity like murder and staging the scene would have been impossible.
Breaking down the timeline, Ma Cong did not lie. Mo Yun indeed died before 9:40 PM, specifically between 8:45 AM and 9:40 AM.
"Do you think the killer's original target was Mo Yun, or was it simply to frame Li Yang?" This was what Lü Qingqing couldn't figure out.
If the killer's primary target was Mo Yun, then the motive for murder becomes the breakthrough point. Mo Yun's financial situation, romantic relationships, personal grudges, etc., could be investigated.
But if the killer merely intended to frame Li Yang, and Mo Yun was an unfortunate victim, then the investigation would be much more difficult.
"I think it's the latter, but it doesn't preclude elements of the former being involved," Hu Jia said, adding, "After all, they specifically stole Li Yang's shoes, indicating premeditation."
The time of death was established.
What needed to be confirmed was how the killer entered Mo Yun's room and how they killed him.
On the night of the incident, only three auxiliary staff members were on duty at the school.
They were Mo Yun, Ma Cong, and a female auxiliary staff member named Chen Keqin.
The police had questioned Chen Keqin, who reported seeing no suspicious individuals that day. The entry and exit log for the training institute also showed no abnormalities.
As mentioned earlier, a witness saw Mo Yun at 9:30 PM. This witness was Chen Keqin.
She said she heard something unusual outside, as if something had hit the door, so she went to look. She happened to see Mo Yun closing his door.
She assumed Mo Yun had dropped something outside and didn't pay it further attention.
It was only ten minutes later, upon hearing Ma Cong's exclamation, that she realized Mo Yun had met with foul play.
"Let's go! We need to question the witness ourselves," Hu Jia said after reviewing the entire case file, sensing something unusual.
...
"Describe again how you discovered Mo Yun's murder." Hu Jia found Ma Cong.
"I was on my way back to the dormitory. When I passed Mo Yun's room, I saw him lying in a pool of blood. I then shouted, which alerted Chen Keqin. I asked her to secure the scene while I went to Tongyuanmen to report it," Ma Cong recalled.
"Why did you decide to check his room? Weren't you afraid of disturbing him so late?"
"It wasn't me who wanted to check; his door was already open."
"Why did you leave the training institute so late, and why did you happen to see Li Yang climbing the wall?"
"I was going out for a late-night snack at Old Chen's noodle shop nearby. The owner can vouch for me."
"Did you not see Li Yang being beaten up, as he claimed?"
"No! I only saw him climbing over the wall alone."
...
"Are you sure you saw Mo Yun at 9:30 PM? Why do you remember so clearly?" Hu Jia summoned Chen Keqin again.
"The school duty roster is posted at the gatehouse, teaching building, logistics building, and other locations. We have to sign in every two hours. It was my turn at 9:30 PM, and I happened to be going out then, so I remember the time precisely."
"What was his situation when you saw him?"
"He was just closing his door."
"Did you hear any unusual noises that night? Such as sounds of a struggle."
"No, it was quiet the whole time."
...
After a round of questioning, Hu Jia fell silent.
Chen Keqin saw Mo Yun closing his door at 9:30 PM. Ma Cong discovered Mo Yun's door ajar at 9:40 PM.
There was only a ten-minute gap in between. If someone was framing Li Yang, he wouldn't have had enough time to commit murder, stage the scene, and escape.
Therefore, the Tongyuanmen police concluded that the killer could only be Li Yang, as only he could have committed the murder and fled the scene within 10 minutes, fitting the timeline of him climbing the wall at 9:40 PM.
After all, Li Yang wouldn't need to stage the crime scene.
Hearing Hu Jia's analysis, Lü Qingqing also felt a strong sense of unease. She had to admit, the killer's plan was exceptionally brilliant.
If they didn't know Li Yang personally, they might have also believed he was the killer.
"This is a dead end. Is there truly no way for Li Yang to escape?" Yu Yue's face turned pale. For a long time, she had grown accustomed to Li Yang's constant "Xiao Yueyue." Suddenly not hearing it left her feeling lonely.
Moreover, to say Yu Yue had no feelings for Li Yang would not be entirely accurate. She might have just not understood her own heart.
Otherwise, try having someone else call her "Xiao Yueyue," and she would likely point their pen tip at you and curse.
"There will be a way. No matter how perfect the trap is, we will find its flaw," Lü Qingqing said, her heart aching seeing Yu Yue on the verge of tears.
Just as it is said—
Only after loving do you know deep affection; only after losing do you know the value of love.
"Let's go find Li Yongqiang again. He was the one who directed you to Mo Yun," Hu Jia said, extinguishing a cigarette butt.
"You suspect him?" Lü Qingqing asked, confused.
"No, I suspect he was also caught in a trap," Hu Jia replied.