The photo shows an ashtray on the coffee table, right beside the body's left hand, with two bits of ash remaining inside.
But there are only ashes, no cigarette butt.
Lu Chuan had already seen the autopsy report; the victim Zhang Wen's right hand index and middle fingertips were yellowed with obvious smoke stains, clearly indicating a history of smoking.
For a smoker, having ash in the ashtray on the coffee table is perfectly normal.
The question is, why is there ash, but no cigarette butt?
Lu Chuan looked pleasantly surprised and continued to flip through the photos. Moments later, a photo of a trash can at the victim's doorstep appeared on the screen.
A cigarette butt was conspicuously at the bottom of the trash bin!
Zooming in on the photo, the brand on the cigarette butt had burned away, and the end connecting the filter to the tobacco was scorched.
Being a smoker himself, Lu Chuan clearly understood this situation arises when the smoker doesn't snuff out the cigarette, allowing the butt to burn naturally.
Is this cigarette butt left by Zhang Wen?
Lu Chuan frowned, and flipped through a few more photos. This time, a cigarette box appeared on the screen.
Lu Chuan had numbered and photographed every item on the coffee table.
Hongmei brand cigarettes, with a lighter beside the pack, were likely Zhang Wen's usual smoke.
These cigarettes aren't expensive. When Lu Chuan was in college, classmates often bought them, and Lu Chuan had smoked them as well.
Therefore, he was quite familiar with these cigarettes.
And because of this familiarity, he noticed the problem.
The Hongmei cigarette filters are different from ordinary cigarette filters, marked with light yellow dots.
However, the cigarette butt in the trash can didn't have those light yellow dots on the filter.
Which means the unbranded butt in the trash can likely wasn't smoked by Zhang Wen.
If it wasn't smoked by Zhang Wen, who left it there?
An excitement flashed in Lu Chuan's eyes; could it be left by the murderer?
He turned and looked at the sleeping Liu Guodong, deciding to wake him up as the cigarette butt had not been collected as evidence, necessitating a revisit to the scene.
But revisiting requires procedure; no one is allowed to enter the scene alone, and at least two people must conduct it, along with a third witness.
Of course, rules are rigid, but people are flexible. In most situations, an auxiliary police officer serves as the third witness.
It's much like a middle-aged man; even if prostate troubles mean he can't perform, fingers can still be used.
A drowsy Liu Guodong was startled by the excited look in Lu Chuan's eyes as he woke up.
"A lead?"
Lu Chuan nodded excitedly, his hair fluffed up like a messy bird's nest, "Zhang Wen smoked Hongmei, but the cigarette butt in the trash isn't Hongmei. I feel there's something wrong."
After Lu Chuan explained, Liu Guodong straightened up instantly. Although tired from the day's work, his interest was piqued.
"Let's go to the scene!"
"Should we report to Captain Qin?"
"No need. Let's first retrieve the stuff, and after collecting the DNA information, we'll report it when the evidence is conclusive!"
Experience speaks volumes; don't engage without certainty.
Lu Chuan and Liu Guodong left without disturbing anyone. The first meeting room remained noisy, and Qin Yong's angry shouting echoed throughout the team building.
Of course, no one was paying attention to the crime scene investigation at this moment; their tasks had essentially been completed.
Liu Guodong hadn't gone home partly because he felt awkward leaving Lu Chuan alone.
Another factor was that the case remained unsolved, and leaving would show disrespect and challenge Captain Qin Yong.
An old hand in the field couldn't do such a thing.
Watching the vibrant Lu Chuan, his eyes shining with excitement, Liu Guodong felt as though he was back to when he had just joined twenty years ago.
"Being young is great..."
One hour later.
By the DNA analyzer, Liu Guodong closely watched Lu Chuan operating the equipment, "How is it?"
Whew!
Lu Chuan took the comparison report, exhaling a long breath, "The DNA on the cigarette butt is confirmed not to be Zhang Wen's."
Damn!
Liu Guodong excitedly grabbed the report, giving Lu Chuan's shoulder a firm pat, "Well done!"
"You've hit the jackpot... Hmm?"
Liu Guodong's excited demeanor gradually solidified, turning into disbelief: "This DNA match…"
Lu Chuan shook his head, "That's right, the DNA on the cigarette butt isn't Zhang Wen's but has a parent-child relationship…"
"The cigarette butt was left by his son."
Shit!
At 5:20 in the morning.
Twenty-six hours had passed since Zhang Wen's death, and there were still no breakthroughs in the case in the first conference room.
As the Chief of the Criminal Investigation Team, Qin Yong had worked his way up from a frontline police officer, handling more than twenty murder cases himself.
Even though the majority of those cases were solved, no one can guarantee a murder case will always be cracked.
In Zhang Wen's murder, no valuable clues have been found so far.
Generally speaking, there is a saying of the golden seventy-two hours in solving murder cases, meaning the chances of solving them are greatest within three days after the incident.
That's not to say it cannot be solved after this time, but it would require more time and effort.
"Everyone, conduct a comprehensive investigation around Zhang Wen's home; no household should be missed, everyone must be fully interviewed and investigated."
"Expand the monitoring scope as well, go through all surveillance footage within a kilometer of Zhang Wen's house, at each intersection and shop!"
In the absence of clues, a manhunt tactic is the best tool for the criminal police to solve the case.
This is also one reason for the golden seventy-two hours; three days of a manhunt tactical siege is generally the limit for most people.
Bang!
The door of the first meeting room was violently pushed open, drawing all eyes to the entrance.
At this moment, everyone wanted to see who dared enter the first meeting room.
Qin Yong's attention was also drawn, finding it was Liu Guodong from the Crime Scene Investigation office, his cloudy expression clearing slightly.
Liu Guodong was a veteran, having joined the force at the same time as Qin Yong. Although currently without an official position, he led the crime scene investigation, making him a key technical asset of the team.
Qin Yong checked the time; it was nearly 6 a.m.: "Old Liu, why haven't you gone to rest after a busy day of investigation?"
Liu Guodong shook his head, directly interrupting Qin Yong, "Captain Qin, we have a lead!"
A lead!
Qin Yong leaped up from his seat, his tired eyes glinting with sharpness, "Did the Crime Scene Investigation find something?"
Liu Guodong nodded heavily, handing the DNA comparison report of Zhang Wen and the cigarette butt from the trash can to Qin Yong, "The cigarette butt at the entrance of Zhang Wen's house isn't the deceased's, but his son's!"
His son's?
Qin Yong felt a surge of joy!
Zhang Wen's son, Zhang Minlu, didn't usually live with Zhang Wen.
Yesterday morning, Zhang Minlu had gone to pick up Zhang Wen for a physical examination and found him dead, then reported the case.
If they didn't live together, how could a cigarette butt smoked by Zhang Minlu be in Zhang Wen's home?
Could it be that after seeing his father dead, he smoked a cigarette while reporting the case?
"Old Liu, if the case is solved, your Crime Scene Investigation will take the credit!"
"Team one and two, immediately follow me to Zhang Minlu's house!"