"Lu, the handlebars are crucial. Whether the suspect pushed or rode the electric scooter, the handlebars are parts the murderer must have touched."
Yang Sen mimicked the posture of riding an electric scooter, analyzing the parts the murderer might have touched.
"There are no people within a two-kilometer radius of Happy Reservoir, so it's unlikely the suspect pushed the scooter..."
Liu Guodong picked up a flashlight, shining it on the scooter's step to see if there were any footprints.
If the suspect pushed the scooter, they wouldn't touch the step, but if they rode it, there would be footprints on the step.
Old Bai was cleaning hair from the rear wheel bearings: "The body must have been draped across the back seat, that's how the hair got tangled in the bearings."
"Ding!"
"Advanced task: Conduct an inspection of the electric scooter, gather fingerprint data to help the action team narrow down suspect identification, and solve the Happy Reservoir body case."
Lu Chuan, who accepted the task, focused on observing the rear seat's handle position.
To push the scooter into the reservoir, the suspect's fingers were likely to touch the rear seat handle.
While Lu Chuan and others were inspecting the scooter, the action team's detectives were also rapidly advancing their work.
"Captain Qin, we've identified the origin of the electric scooter."
Ren Qiang held the registration information from the traffic police: "The owner is named Wang Song, who runs a small restaurant."
"It was stolen three days ago, and the local police station has Wang Song's theft report."
Three days ago was exactly when the victim was murdered.
"Where was the scooter stolen?"
"Number 28 North Lake Road, right outside Wang Song's restaurant."
"Is there surveillance footage?"
Ren Qiang shook his head: "The scooter was parked in a blind spot, and no trace of the thief was found."
"Check, conduct a focused investigation on Wang Song," Qin Yong contemplated for a moment, then began assigning the next tasks.
Qin Yong had seen many cases of staged thefts by the owner.
"And contact the traffic police. The suspect would have left behind surveillance footage while stealing and abandoning the scooter."
"Confirm all traffic routes from Number 28 North Lake Road to Happy Reservoir, retrieve all surveillance footage, leave no stone unturned!"
What is a homicide mechanism? It means deploying the greatest possible resources to solve the case in the shortest time!
Within the team courtyard.
Liu Guodong and others looked grimly at the scooter, feeling somewhat helpless.
"Old Liu, the scooter has been soaking in water for too long. We cannot retrieve fingerprints at all."
In one afternoon, there was no progress in the crime scene investigation.
On the other hand, Old Bai had already completed the DNA analysis.
The hair found in the scooter's rear wheel bearings belonged to the deceased.
At this moment, only Lu Chuan was crouched down, meticulously inspecting every part of the scooter inch by inch.
Liu Guodong remembered the complete fingerprints Lu Chuan had extracted from the body in the morning.
And the fingerprint extraction he assisted with at the arson scene investigation days ago with Ren Qiang's Second Action Team.
Given Lu Chuan's careful and earnest demeanor now, hope sparked in Liu Guodong's heart.
"Lu, do you have any ideas?"
Though Lu Chuan frowned slightly at the moment, his expression was relatively relaxed.
The system-issued Intermediate Fingerprint Collection Skills included many techniques and methods.
Especially regarding fingerprints damaged by fire or water, specialized fingerprint collection methods were available.
This electric scooter involved in the case had soaked in water for three days, yet Lu Chuan still had a way to collect the remaining fingerprint information.
"Master, I found something."
Lu Chuan took a UV lamp from the crime scene box and began scanning the handlebars, rear seat, and step of the scooter.
"I have closely observed these areas, and there are no traces of them being wiped."
Liu Guodong nodded: "Indeed, there's no trace of wiping; there should be fingerprints there, but soaking in water makes extraction impossible."
Liu Guodong had already tried both physical and chemical methods but failed to extract any fingerprints.
After three days of soaking, the sweat forming the fingerprints had long dissolved.
Even the water-insoluble portion of the oils had faded away, preventing fingerprint visualization after prolonged soaking.
In crime scene investigation, water-related cases are the most challenging.
The longer the time, the fewer things can be discovered.
Lu Chuan nodded: "Indeed, conventional methods cannot extract fingerprints after soaking, but some special methods can still work."
Turning off the UV lamp, Lu Chuan relaxed his brow: "There will be some issues with the completeness of the fingerprints extracted this way."
Oh?
The completeness is an issue, but extraction isn't impossible?
Liu Guodong raised his eyebrows: "Lu, are you saying you can extract them?"
"Yes, but I need to make some preparations."
An hour later.
Lu Chuan returned to the courtyard.
This time, he was holding a small spray bottle.
During this hour, Liu Guodong and the others followed closely behind Lu Chuan.
They witnessed Lu Chuan evolve from a crime scene investigator into a... chef.
Yes, a chef.
The guy had been wandering around the team kitchen for the past hour.
He searched through all the bottles and jars inside.
He mixed up a bottle of a dark substance.
"Lu... will this work?"
Old Bai was somewhat puzzled, not understanding the specifics of Lu Chuan's actions, but he knew Lu Chuan was making a homemade fingerprint agent.
But wasn't this something legendary experts would do?
Lu Chuan... is making his own fingerprint agent?
Liu Guodong's eyes narrowed slightly, watching the spray bottle in Lu Chuan's hand: "Lu Chuan... Are you confident?"
Fingerprint agents were issued to the Criminal Investigation Team by higher-ups.
The ingredients were quite simple, primarily water and some chemical coagulants.
These fingerprint agents were uniformly distributed nationwide, structurally stable, and commonly used in crime scene investigations.
However, before these standardized agents, each region had its own preferred fingerprint agents.
Historically, unstable agents often destroyed fingerprints at crime scenes.
Therefore, homemade fingerprint agents were no longer allowed.
Lu Chuan's ability to make his own agent demonstrated that his fingerprint collection skills surpassed those of Liu Guodong and the others.
But on the other hand, if the agent had issues and destroyed the fingerprints on the scooter, Lu Chuan would be responsible.
If the scooter had soaked for three days and fingerprints couldn't be collected, it was understandable; no one would blame the crime scene office personnel.
At worst, they would report to the provincial department and have higher-level experts take a look.
But if the agent destroyed the fingerprints and higher-level experts couldn't collect them, Lu Chuan would be to blame.
This is why cutting-edge technology is rarely used in criminal investigations.
Pursuing stability is the lifeline of the criminal investigation field.
Lu Chuan clearly understood Liu Guodong's concern.
He was showing care for him.
As for concealing the use of the agent—that was impossible.
Fingerprint agents are chemical substances, leaving traces upon use.
These must be recorded as procedural requirements; no one could violate these protocols.
So, should Lu Chuan take the risk?