The sun is rising!
The morning light enveloped the earth.
The number of pedestrians on Dajing Chaoyang District Road is gradually increasing.
Chaoyang Investigation Bureau, Forensic Science Laboratory.
"Team Leader Shen, we've identified the foreign object causing the motorcycle engine malfunction."
Upon hearing Shen Ting's question, Director Ma handed Shen Ting an appraisal report directly.
Shen Ting took it and began to quickly flip through it.
Director Ma also introduced:
"The culprit is metal shavings."
We found a lot of sharp, angular metal particles in that engine.
These particles are fundamentally different from the rounded metal particles formed by wear and tear during engine operation.
Larger and sharper!
We conducted a relatively detailed analysis of these particles.
Its composition is quite ordinary.
These are the most common steel bars found on construction sites.
Guan Guandu, who was standing next to Director Ma, smiled and said:
"This result proves that your judgment, Team Leader Shen, was correct."
It is true that someone deliberately threw steel scraps at Wu Liqun's motorcycle, damaging it.
This can easily cause serious accidents, ranging from broken legs or arms to death.
Wu Liqun was able to dodge three times; he was really lucky.
I have a feeling that the person who threw the steel scraps and the person who killed Wu Liqun and his wife are most likely the same person.
Oh, right…
Guan Guan suddenly remembered something and said:
"Team Leader Shen, you asked us to investigate whether the staff at the motorcycle repair shop had any conflicts with Wu Liqun."
The results have just come in!
We questioned several employees at the motorcycle repair shop separately.
We asked almost everyone, especially those who weren't directly involved in the repairs.
They all said that there had been no conflict between the maintenance personnel and Wu Liqun.
We also contacted the owners of other shops in the area.
They also had no recollection of any recent conflict occurring at the repair shop.
Shen Ting nodded.
However, the repair shop staff may be lying.
The shop owner next door couldn't possibly know the full details of the repair shop's situation.
They had no idea who Wu Liqun was.
Therefore, the investigation in this regard is questionable.
Shen Ting directly shared the investigation video on this matter and asked Yao Xuechen to help review it.
Yao Xuechen: "Judging from micro-expressions and body language..."
The repair shop staff did not lie or conceal anything.
Then there shouldn't be any problem.
The motorcycle repairman can be largely ruled out as a suspect.
"that is!
It is now confirmed that someone has repeatedly tried to harm Wu Liqun via motorcycle.
However, the ordinary steel rebar found in the engine was insufficient to identify the suspect.
Even suggesting that Zhao Weijun, who runs a construction team, is more suspicious, is somewhat far-fetched, given that steel bars are commonly found on construction sites.
Because steel bars are so common.
In rural areas, building a house requires a lot of these materials.
"I remember that even though they are all steel bars, the specific components inside are different."
Different batches of steel bars have different chemical compositions and microstructures.
Even steel bars from the same batch can have slight differences.
The precise content of alloying elements such as manganese, silicon, vanadium, and titanium in steel bars is determined by identification.
By using a metallographic microscope to measure grain size and determine the composition ratio of phases such as ferrite and pearlite, a more detailed distinction can be made between steel bars.
"It would be possible to take large-scale samples of the steel bars on Zhao Weijun's construction site, or even the steel bars on Wu Liqun's construction site, for testing."
However, it doesn't seem to have reached that point yet.
Shen Ting was not used to this kind of investigative approach.
Just like what Captain Zheng mentioned before, because it was uncertain where the killer's special smell came from, but since auto repair shops are the most common, the investigation was arranged to focus on auto repair shops in Chaoyang District.
Such an investigation approach is essentially like taking a chance.
Moreover, it is time-consuming and labor-intensive.
Shen Ting didn't like it very much.
Of course, that doesn't mean there's absolutely no chance of finding clues in these directions.
When you're really at your wit's end, it's good enough to have a direction for investigation; who cares if it's just a matter of luck?
However, this case hasn't reached that stage yet.
Shen Ting thought for a moment and then asked the head of the forensic laboratory:
"Director Ma, I remember that when we examined the fibers in Zhao Huimei's fingernails and Wu Liqun's wound, we found some oil stains."
Metal particles were also found in it.
The explanation given at the time was that those metal particles were formed by mechanical friction.
Can we pinpoint the exact source of those metal particles?
Overall, the case is not very clear.
But the direction is clear—
Looking for those two people, one fat and one thin.
The most definitive evidence they left at the crime scene was the distinctive oil stain.
This clue is even more indicative than the footprints at the crime scene.
only!
There's been some trouble figuring out how to find the two murderers.
All that can be confirmed is that they work in the mechanical field.
If we can determine the specific direction of mechanical work they were engaged in by examining the metal in the oil, we might make an unexpected discovery.
Even without particularly special physical evidence, this can further narrow down the suspect's search area.
Upon hearing this, Director Ma frowned slightly and said:
"Those metal particles can indeed be further identified."
However, it is usually necessary to find a professional metal materials testing agency to conduct the test.
Team Leader Shen, you know him.
Identifying metals, especially such tiny metal particles in oil stains, requires highly specialized knowledge in materials science.
However, this type of assessment may not need to be conducted even once a year.
Recruiting relevant personnel for the Investigation Bureau would be too costly and would also delay their work.
Therefore, when needed, we usually seek help from social organizations for identification.
Team Leader Shen, if needed this time, I can make the contact.
Or, Team Leader Shen, why don't you give it a try?
Director Ma looked at Shen Ting with anticipation.
As the director of the identification room of the Chaoyang Investigation Bureau, Director Ma was always present when Shen Ting conducted pollen identification and trace evidence identification.
Therefore, he naturally knew that Shen Ting's level of forensic identification was very high.
The key point is!
He learns a lot every time he watches Shen Ting's appraisal.
Shen Ting didn't agree immediately. After thinking for a moment, he asked:
"How accurate are the results if you go to a professional appraisal agency in the community?"
Can you guarantee the accuracy of the test results?
Also, how long will the identification process take?
...
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