"Xiao Lu, the handlebar is the key, whether the other party is pushing an electric car or riding an electric car, the handlebar is the part that the murderer must touch."

Janssen imitates the attitude of the electric car and analyzes the places where the murderer may have touched.

"There are no people in the two kilometers around the Xingfu Reservoir, and it is unlikely that the other party is pushing an electric car......"

Liu Guodong picked up a strong flashlight, shone it on the pedal of the electric car, and carefully observed whether there were footprints in the room.

If you push an electric car, the other party will not be able to touch the pedal, but when you ride an electric car, you will inevitably leave footprints on the pedal.

Lao Bai was cleaning the hair in the rear wheel bearing: "The corpse should have been lying on the back seat at that time, so that the hair would be rolled into the bearing." ”

"Ding!"

"Advanced mission: Through the investigation of electric vehicles, fingerprint information is collected to help the action team lock the scope of the suspect and solve the case of the sinking of the body in the Happy Reservoir."

Lu Chuan, who accepted the task, paid attention to the position of the handrail in the back seat.

The killer wanted to push the electric car into the reservoir, and there was a good chance that his fingers would touch the handrail of the back seat.

While Lu Chuan and others were surveying the electric vehicle, the investigation and criminal police of the action group were also rapidly advancing their work.

"Team Qin, the origin of the electric car has been clarified."

Ren Qiang took the electric vehicle registration information given by the traffic police: "The owner's name is Wang Song, and he opened a small restaurant." ”

"It was stolen three days ago, and the local police station has Wang Song's police record."

Three days ago, it was the time when the victim was killed.

"Where was the electric car stolen?"

"No. 28 Beihu Road, right at the door of Wang Song's restaurant."

"Is there any surveillance footage?"

Ren Qiang shook his head: "The car was parked in the dead corner of the surveillance, and no trace of the car thief was found." ”

"Check, focus on this Wang Song," Qin Yong thought for a moment and began to arrange the next tasks.

Qin Yong has seen a lot of self-theft.

"There is also contact with the traffic police, the murderer stole the electric car and threw the body, and he will definitely leave video data along the way."

"Determine all the passage sections from Beihu No. 28 to Xingfu Reservoir, call up all the monitoring, and not let go of any of them!"

What is the homicide mechanism, is to do the best possible, invest the most resources, and solve the case in the shortest possible time!

Inside the courtyard of the detachment.

Liu Guodong and others had hazy eyes, looking at the electric car in front of them, a little helpless.

"Lao Liu, the electric car has been soaked in water for too long, and there is no way to extract fingerprints."

For an afternoon, there was no progress on the current survey.

However, Lao Bai's side has already completed the comparison of DNA information.

The hair in the rear wheel bearing of the electric car is the deceased.

At this moment, only Lu Chuan was squatting on the ground, scanning every part of the electric car inch by inch.

Liu Guodong remembered that Lu Chuan's corpse fingerprints were taken in the morning, which were extremely complete.

There is also the matter of helping Ren Qiang of the second group of operations to extract fingerprints at the scene of the arson case in the southern suburbs a few days ago.

Coupled with Lu Chuan's careful and serious appearance now, he has expectations in his heart.

"Xiao Lu, do you have anything to do about this?"

Although Lu Chuan was also frowning slightly at the moment, his expression was still relatively relaxed.

The system rewards intermediate fingerprinting skills, including many skills and methods.

In particular, there are special fingerprint collection methods for dealing with fire and blisters.

Although the electric car involved in the case was soaked in water for three days, Lu Chuan still had a way to collect residual fingerprint information.

"Master, I have made some discoveries."

Lu Chuan took out a purple light from the survey box and irradiated the handlebars, back seats and pedals of the electric car.

"I've looked at these places carefully, and there's no trace of wiping them."

Liu Guodong nodded: "There is indeed no trace of wiping, there should be fingerprints on it, but after soaking in water, it can't be extracted at all." ”

Liu Guodong has just tried, and ordinary physical and chemical methods have no way to extract fingerprints.

After three days of soaking, the sweat that formed the fingerprints had long since melted.

Even the water-insoluble part of the oil is diluted after a long time of soaking, and fingerprints cannot be developed.

In this line of investigation, the most feared thing is the case of water.

The more time passes, the less you can discover.

Lu Chuan nodded: "After soaking, it is true that conventional methods cannot extract fingerprints, but there are some special methods that can still have some effect." ”

Turning off the purple light, Lu Chuan's brows stretched: "Even in the completeness of fingerprint extraction, there will be some problems." ”

Oh?

There's a problem with completeness, but it's not that it can't be extracted?

Liu Guodong's eyebrows raised: "Xiao Lu, do you mean that it can still be extracted?" ”

"Yes, but I'm going to prepare."

An hour later.

Lu Chuan returned to the courtyard again.

This time, he had a small watering can in his hand.

For this hour, Liu Guodong and the three of them followed behind Lu Chuan.

Witness how Lu Chuan evolved from a criminal police officer to a ...... Cook.

Yes, chef.

This guy has been hanging out in the detachment kitchen for the past hour.

I flipped through the bottles and jars inside.

Makes such a bottle of black stuff.

"Xiao Lu...... You ...... Can it be done? ”

Lao Bai was a little confused, although he didn't understand the details of what Lu Chuan did, he knew that Lu Chuan was making his own fingerprint developer.

However, isn't this thing a legendary master?

Lu...... Homemade fingerprint developer?

Liu Guodong's eyes were slightly condensed, and he looked at the small watering can in Lu Chuan's hand: "Lu Chuan...... Are you sure? ”

Fingerprint contrast agent, which is available in the criminal investigation detachment, is distributed from above.

In fact, the composition is very simple, mainly water, and some chemical coagulants.

This kind of fingerprint developer is commonly used throughout the country, with stable structure, and is a commonly used material for the extraction of fingerprints in the field survey.

However, before the unified distribution, each place had its own commonly used fingerprint contrast agent.

Historically, there have been many cases where the on-site fingerprints have been destroyed due to the instability of the contrast agent.

Therefore, later homemade fingerprint contrast agents were not allowed to be used.

Lu Chuan can make his own contrast agent, which on the one hand shows that Lu Chuan's strength in collecting fingerprints has surpassed that of Liu Guodong and the others.

But on the other hand, if there is a problem with the developer, it destroys the fingerprint on the electric car.

This responsibility is Lu Chuan's.

It is normal for the electric car to be soaked in the water for three days without fingerprint collection, and no one can blame the people in the survey office.

The big deal is to report to the provincial department and let the experts from above come to investigate.

However, if the developer destroys the fingerprint, the experts from above will not be able to collect the fingerprint.

Then this responsibility is Lu Chuan's.

This is why cutting-edge technology is rarely applied in the field of forensics.

Seeking stability is the lifeline of the field of criminal investigation.

Lu Chuan obviously understood the meaning of Liu Guodong's words.

He's caring about himself.

As for the concealment of the use of contrast agents, this is impossible.

Fingerprint developers are chemicals that are sure to leave marks after use.

These must be documented, this is a process issue, and no one can go against it.

So, should Lu Chuan take the risk?