Chapter 977: Clues from Trace Evidence Identification

Zhang Mengyao’s body was found inside the Experimental Primary School, which is where he worked.

Not to mention why the murderer did this, just the fact that the murderer was able to place the sculpture inside the Experimental Primary School indicates that the perpetrator must be quite familiar with the Experimental Primary School.

Analyzing from this clue, there is a very high possibility that the perpetrator works at the Experimental Primary School.

So, when Zhang Mengyao left the school back then, who else left with him?

From the investigation of Zhang Mengyao’s residence, it seems that there is no possibility he returned home alone.

Either he didn’t return home, or if he did, he took a car through the underground parking garage.

Because there is surveillance at the entrance of the residential area, if Zhang Mengyao returned home alone, he should have gone through the entrance as he usually did, and the surveillance would have definitely captured him. Thus, during the investigation of Zhang Mengyao’s missing case back then, this point should have been looked into.

So he either didn’t return home, or if he did, it should have been by car through the underground parking garage.

Based on the scene investigation, Lu Chuan is more inclined to believe the second possibility.

Because Zhang Mengyao was wearing a lace camisole dress when she died, it is very likely hers.

Then the question arises.

Zhang Mengyao didn’t have a boyfriend at that time, so who did she go home with? Moreover, she left the school early.

Frame by frame, the surveillance footage was reviewed, and every person entering or leaving the school was marked by Lu Chuan.

Soon, a total of four people were marked.

After Lu Chuan called Zhang Hui over, he directly gave him the information on these four people.

"Brother Hui, check out these individuals first. Zhang Mengyao only left the school around the time these people did. They left early."

After Zhang Hui received the surveillance screenshots of the four individuals, he said, "Eh? I know this person."

Among the four people, Zhang Hui pointed at a slightly chubby middle-aged man.

Ever since Zhang Mengyao’s body was discovered, Zhang Hui had already gotten a good grasp of the situation at the Experimental Primary School, having met almost all the teachers.

"Who is this?"

"The principal, who was the vice-principal of the Experimental Primary School back then, got promoted to principal two years ago."

Lu Chuan nodded and, not paying much attention, continued, "Moreover, check the personnel, including staff and all other personnel, who took leave from the school on the day Zhang Mengyao disappeared to see if there’s anything we can find out."

"Alright, I’ll arrange for that."

By the time Lu Chuan finished checking the surveillance, it was already past four in the morning, so it was naturally not the time to visit the school.

Returning to the office in Hong Kong, Liu Guorong and the others hadn’t gone home this time either, having worked through the night and were now napping on the sofa for a temporary rest.

There were four sofas in the office, all of which were occupied. Lu Chuan thought it was time to head home rather than stay here.

The next morning.

Lu Chuan and Shen Yan went to work together.

"I’ll drop you off at the Criminal Investigation Team first, then head over to the other department to have a look."

Lu Chuan was only there to assist with the case, so naturally, he couldn’t skip his own work to stay at the Criminal Investigation Team.

"Alright."

Shen Yan obviously hadn’t been resting well lately.

His eyes were slightly swollen and had dark circles, a clear sign of lack of sleep.

However, there was no way Lu Chuan could persuade him otherwise; dealing with a homicide case often meant working overtime without rest, and no one on the team could really get a good night’s sleep.

Over at the Criminal Investigation Team, Zhang Hui hadn’t gone home the night before, and as soon as dawn broke, he took the information on the individuals Lu Chuan had identified and hurried over to the Experimental Primary School.

He verified what was happening with these four people one by one, asking why they left that day, whether there were any witnesses, and so forth.

Time passed by quickly, and in the blink of an eye, another two days had gone by.

During these two days, Lu Chuan hadn’t gone to the Criminal Investigation Team, but Zhang Hui did come over.

However, judging by the weary expression on Zhang Hui’s face, it seemed that there hadn’t been much progress in the investigation of the case.

After pouring Zhang Hui a glass of water, Lu Chuan asked, "So, what do you have on those people?"

Zhang Hui shook his head.

"The principal went to a meeting at the Education Bureau. Of the remaining three, one is a PE teacher who usually leaves early, another is a math teacher who took leave for personal matters, and the last is a janitor who also requested leave for personal reasons."

To be honest, this case had too few clues. Zhang Hui originally felt that Lu Chuan had provided some clues that might have helped them gain some ground.

But after two days had passed, he had already screened all teachers or other staff who weren’t at the school when Zhang Mengyao disappeared.

It turned out there was no new discovery; those who took leave that day had legitimate reasons and witnesses to back them up.

Lu Chuan sighed.

That’s how cases are sometimes - you might chase down every clue with no guarantee of a good outcome.

"We’ll just have to rely on the trace evidence analysis from the master now."

Lu Chuan comforted Zhang Hui.

We can only hope the murderer left some trace when dealing with the plasterwork.

Otherwise, it truly would be a tough case to crack.

Time flew by quickly.

In a flash, another week had passed; over at the Criminal Investigation Team, there were some minor cases, but Lu Chuan delegated them to a few squad leaders without getting involved personally.

The Criminal Investigation Team’s case was still being pushed forward, but other clues had essentially come to a standstill, leaving only some basic field investigations.

Liu Guodong and his team, however, worked overtime every day for the entire week, as conducting trace element analysis is meticulous work to begin with, and given the large quantity this time, it was extremely challenging for them.

For this kind of work, it has to be done with utmost care and seriousness; missing any piece of evidence, however small, could lead to inadvertently overlooking the traces left by the suspect.

Thus, extracting even the smallest specimen or bit of glass required a tight collaborative effort from several people, each task done with utmost vigilance.

On the 20th day following the incident.

At the Criminal Investigation Team, Yang Lin hadn’t been home since the incident.

He spent his days holed up in the lab of 1.5 Middle School, conducting experiments day in and day out with no end in sight.

Old Bai, however, couldn’t keep up due to his age and health, so for the past several days, Old Bai had been going home to sleep at night.

"Yang Lin, the extraction of specimen No. 167 is almost done. Go and process this one."

Yang Sen had been working overtime for twenty days as well, so busy he hadn’t even had the time for a shave, leaving him looking rugged and worn.

"Alright, I’ll get to it."

Having just completed another specimen analysis, Yang Lin hurried to place the extracted specimen No. 167 into the instrument for processing.

Extraction within the field of trace substance analysis is quite time-consuming, but once extraction and pre-treatment are completed, the identification process tends to be relatively quick.