After observing for five minutes carefully, Zhang Yean shook her head in disappointment.

"The surface here is too rough to leave any fingerprint traces."

Jiang An removed his mask and sniffed the area where the oil residue was.

"I can't tell what kind of oil it is just by using my nose."

Then Zhang Yean and Wan both held the steel bar close to their mouths and sniffed it.

"It seems to have been exposed to the outdoors for a long time, and the oil has evaporated."

Jiang An asked, "Mr. Li, do we have the means to identify the type of oil in Jiangcheng City?"

"I'm not sure about this kind of special substance identification."

"We'll have to check with the Environmental Protection Bureau or the Food and Drug Administration."

Jiang An added, "If we have the capability to conduct oil component analysis, it would help us profile the perpetrator."

"No problem!"

"If Jiangcheng doesn't have the ability to do the identification, we can completely send this steel bar to a unit outside Jiangcheng for analysis."

Looking at the steel bar, Zhang Yean said, "If this steel bar is the murder weapon, then it means the perpetrator had oil-based substances on their hands."

After thinking for a while, she analyzed, "The incident happened at night, so it couldn't be a vendor selling bulk oil at the market."

"Could it be a worker at a repair shop?"

Upon hearing this, Wan instantly gave a thumbs-up.

"You're quite sharp, sister!"

"You're becoming more and more like Sherlock Holmes."

"You should definitely get the Captain to treat you to chicken legs tonight."

Li Jian smiled knowingly.

"Zhang Yean made a good point earlier, that's indeed a possibility."

Rarely praised by Captain Li Jian, Zhang Yean was overjoyed.

However, she still glanced at Jiang An with her peripheral vision.

If she could get Jiang An's approval, it would be even more rewarding.

Jiang An looked at the steel bar in his hand and said solemnly, "Senior sister, the analysis makes a lot of sense."

"There aren't many people who come into contact with oil, besides everyday cooking, it's mainly mechanics, vendors, and such."

After a brief thought, Li Jian said, "The type of oil can definitely become an important basis for narrowing down the perpetrator."

"However, this is an unfinished building, and there aren't many surveillance cameras around."

"What exactly happened here that night?"

Immediately, all four of them simultaneously looked at the two scratch marks on the ground.

Meanwhile,

Mr. Ma was reviewing documents in his office.

"Ring, ring"

The desk phone suddenly rang.

He put down the document in his hand and glanced at caller ID.

Suddenly, his expression turned serious.

"Mr. Liu! What instructions do you have?"

"Mr. Ma! This time, it's not work instructions, but a work discussion."

Mr. Liu's tone was very tactful, but the breath from the receiver made Mr. Ma feel that there was definitely an issue.

Their kind never makes a visit without a reason.

Mr. Ma's mind immediately went through all the recent work in hand.

Everything seemed fine!

Nothing went wrong.

Especially having solved two murder cases in succession last week, already earning him enough face with the city leaders.

"Mr. Liu, you're the leader, please instruct!"

After a brief pause, the voice on the phone said, "Recently, the economy hasn't been doing well, and many real estate developments are left unfinished."

"Jiangtai Construction Group's site in Hedong resumed work today."

At this point, Mr. Ma immediately found the connection.

So, it's about that case again.

Would an ordinary criminal case really alarm the deputy mayor?

On the phone, Mr. Liu said sternly, "Mr. Ma, I fully support your investigation into the case, but it must not affect the local business environment."

"The resumption of construction by Jiangtai Construction Group involves the housing dreams of many families."

"We've done a lot of work and effort beforehand."

"Moreover, I heard that the case was already concluded."

"Yet your criminal investigation team has gone to the construction site again."

"Today is the ribbon-cutting ceremony for resuming work, and apart from the project manager, workers, there are also homeowner representatives."

"After all, many people now are very superstitious about fatalities occurring on construction sites."

"We must not let unnecessary work affect the project's progress."

"Additionally, police resources are currently strained, and we must focus our limited forces in crucial areas."

A string of statements made Mr. Ma feel strong emotions across the phone.

Mr. Ma promptly replied, "Mr. Liu, thank you for your concern for the policing work in Jiangcheng. Your instructions will definitely be kept in mind."

"Mr. Liu, let me report to you,"

"Regarding the case of Liu Jun's fall from a height three months ago, we've discovered new clues and are moving on to the next phase of investigation."

"Today, the criminal investigation team should be going to the site for a scene examination."

"Is it necessary to re-examine the site for this case?"

"Mr. Liu, this is our procedure for handling cases."

In the end, Mr. Ma said, "Mr. Liu, I was once a criminal investigation team leader, seeking the truth about death cases is what every detective pursues."

"Especially since the new evidence in this case may change the nature of the death."

"Therefore, the criminal investigation team immediately went to the construction site for an examination today, I hope Mr. Liu can understand."

"I guarantee you here that we'll spare no effort to uncover the truth of the case."

After a long silence, the voice on the other end said, "I await your final conclusion."

"But, don't let it end with the same result after much work."

Mr. Ma wanted to say something, but the other party had already hung up the phone.

After a long while, Mr. Ma took a deep breath.

The pressure on him this time was really not small.

If, after investigation, it was still an accidental fall, his current arrangement would be a waste of police resources.

If it turned from an accidental fall to a homicide, then his initial decision would be seen as poor leadership.

Thinking of this, Mr. Ma shook his head.

However, the glory of being a criminal police officer in his bones made him firmly believe that justice comes first.

Randomly, he picked up the landline and dialed Li Jian's number.

"Mr. Ma!"

"Li Jian, proceed with your work according to your own ideas and methods, without interference from anyone."

"Any issues, I'll handle them."

Li Jian was stunned by this sudden admonition, momentarily frozen.

He mechanically replied, "Yes! Mr. Ma!"

Wan walked over and asked, "Boss, does Mr. Ma have new instructions?"

"He told us to proceed at our own pace, without interference from anyone."

As soon as he finished speaking, Li Jian heard a shout from downstairs.

"Captain Li, I'm the chairman of Jiangtai Construction Group, can you come down to talk?"

Upon hearing this, Li Jian went to the window and turned to look down.

"If you're asking us to pause our investigation, there's nothing to discuss."

"Mr. Li, today is the day we resume work, could you delay the investigation by a couple of days?"

"Sorry! That's not possible!"

"I'm a detective, and I only care about the truth."

After saying this, Li Jian turned around and continued examining the scene.

With Mr. Ma as his backing, Captain Li Jian spoke with much more confidence.

Wan instantly gave a thumbs-up, "Boss, you're pretty tough this time!"

Li Jian turned back and said, "No worries! Let's continue investigating the scene."

However, he noticed Jiang An standing there, motionless.

"Have you found something?"

Jiang An replied, "I could hear that man's voice below very clearly."

Wan repeated, "Yes, it was quite clear!"

Jiang An stood by the window and looked.

"This neighborhood has 25 buildings, Building 5 is in the middle."

"When the incident occurred, the site wasn't operating at night, it should've been quite quiet."

Zhang Yean said, "I remember the case file noting that the workers heard construction nearby that night."

"The workers' accommodation was near the east wall, which is quite far from here."

"What does a quiet environment indicate?"

Jiang An was about to answer.

Li Jian's phone rang.

"Captain Li!"

"What's up?"

"The blood alcohol test report for Liu Jun has come back."

"That was quick!"

"We used new equipment this time, doubling the efficiency."

"The test shows the decedent, Liu Jun, had an alcohol level of 82mg/100mL."

"Okay! Thanks for your hard work!"

After hanging up, Li Jian said, "The blood alcohol level of the deceased has come back, 82mg/100mL."

"Just above the threshold for drink-driving!"

Wan said, "With this alcohol concentration, his mind should have been clear."

Li Jian nodded and said, "This concentration is indeed not high."

Jiang An, after hearing this, fell into thought.

With this level of alcohol, when the deceased entered Building 5, his mind should have been very clear.

Moreover, based on the body's alcohol metabolism process, his walking should have appeared normal.

Then, another question surfaced in Jiang An's mind.

If the deceased was sober at the time, did he sense any impending danger?

Even if he was attacked from behind, the assailant must have approached him closely.

Considering how quiet the building is during the day, it would be even quieter at night.

Did the killer really not sense any danger at all?

Seeing Jiang An deep in thought, Captain Li Jian asked, "Jiang An, what are you thinking about?"

Jiang An replied, "The deceased only had one injury to the head, at the top. There were no defensive wounds on his hands or elbows."

"Why didn't the deceased resist?"

"Also, when the elevator had stopped, they both had to walk to the 10th floor, didn't Liu Jun sense anything?"

Hearing this question, Captain Li Jian looked around.

Zhang Yean and Wan both fell into thought.

After a long while, Jiang An said in a low voice, "I'm wondering if there's another possibility."

Zhang Yean was full of curiosity.

"Another possibility?"

"I'm wondering if the deceased and the killer knew each other, which relaxed Liu Jun's guard, giving a chance for a sneak attack."

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