Attending ex-girlfriend's wedding, arresting the groom's officer on the spot

Everyone behind the door did not go up to the rooftop, including Qin Yong, all looked at Lu Chuan eagerly.

"Is it possible that we guessed wrong?"

The roof is only two to three hundred square meters in size, and it can basically be seen clearly at a glance.

If there are traces of dragging, logically speaking, it is most likely to start from the door and extend to the edge of the roof.

However, there is nothing in front of everyone's eyes now.

"Wait a minute, didn't Lao Liu take the spectrometer to see if it works."

Everyone's whispers did not affect Lu Chuan.

That's the way crimes are solved, and of course mistakes can happen.

But you can't stop guessing or thinking about it just because you made a mistake.

What's more, Lu Chuan had some mental preparations for this point.

If there are no drag marks on the rooftop, there are basically only two possibilities.

First, there were no drag marks at all. The friction on Zhou Yang's shoes was caused by other reasons, but Lu Chuan hadn't found the reason yet.

Second, the drag marks did exist, but they were cleaned up by the murderer, so they couldn't be seen with the naked eye.

But it doesn't matter, if you can't see it with the naked eye, it doesn't mean that the instrument can't see it either.

The traces left by rubber dragging, the black surface is easy to clean or wipe off, but the remaining substances cannot be completely disappeared.

Through the spectrometer of special frequency band, it can be seen clearly.

Soon, the portable frequency conversion spectrometer was brought up.

"Xiao Lu, the spectrometer is here."

"Okay, just pass it to me."

Lu Chuan moved his foot pedal and took the spectrometer from Liu Guodong's hand.

Turn on the machine and warm up.

The principle of this thing's light is a bit similar to that of a halogen lamp, and it needs to be warmed up to work.

After a while, Lu Chuan adjusted the corresponding light wave frequency band, and a beam of faint light shone out.

A magical scene happened in front of everyone.

Originally, there was nothing on the ground, but a string of traces extending from the door to the roof were looming.

Wherever the light beam shines, there will be black traces appearing.

"There are really traces!"

After confirming the existence of dragging traces, it can be basically confirmed that Zhou Yang was killed by him.

The nature of the case is determined, and the mentality of the investigators is completely different.

When the corpse was first discovered, they basically followed the normal flow. After all, at that time, no one knew whether Zhou Yang committed suicide or homicide.

And once the homicide is confirmed, the criminal investigation detachment will set up a special case team and report the case, which is a murder case that must be solved.

At this time, everyone's mental tension was completely different from just now.

"Sun Jun, send someone to check all the monitoring in the building."

"Ren Qiang, conduct a thorough investigation of Zhou Yang's interpersonal relationships, find out who Zhou Yang had contact with from last night to this morning, check the phone records, and see who has contacted him."

"Yes!"

After discovering the first crime scene, this place is handed over to the present survey, and the others naturally have other things to do.

Liu Guodong also began to wear equipment, including shoe covers, gloves and even goggles, ready to investigate the scene with Lu Chuan.

"Master, give me the machine. I'll adjust the frequency band to see if I can find the murderer's footprints."

At any crime scene, the murderer is not afraid of vandalism, but the most fearful thing is that the murderer will not move anything.

For example, on this rooftop, the murderer deliberately erased the traces left by dragging Zhou Yang, but this also shows that the murderer stayed on the rooftop for a long time.

In the process of cleaning up the traces, more traces of contact with the scene will definitely be left.

Like more footprints.

But if the murderer left after throwing Zhou Yang downstairs, there would be fewer footprints, and the possibility of the police getting a sample would be smaller.

The frequency conversion spectrum adjusted the frequency again, and the traces of dragging gradually disappeared, and a bunch of dense footprints appeared instead.

"So many footprints?"

There are superimposed and frictional footprints, and there are many traces that are not clear, but because the number is large enough, there are always one or two groups of footprints that are relatively clear.

"Master, give me the camera."

Lu Chuan was also very excited. With so many footprints, it is relatively easy to find a few clear ones and do footprint analysis.

"Master, the footprints are almost ready, come in, let's see if we can get fingerprints."

Lu Chuan stood up and stopped stepping on his feet.

The footprints at the scene have been extracted, and the development under the frequency conversion spectrum just now has been recorded, and the next step can be carried out.

"The edge of the roof is about [-] centimeters high. If the opponent wants to throw Zhou Yang down, he may touch the edge of the roof."

Lu Chuan nodded in agreement and began to wipe his fingerprints.

Under outdoor conditions, fingerprint collection methods in many lighting aspects are not particularly easy to use.

Fingerprints are not like footprints. The texture of footprints is rough, and it is possible that a single print may be thicker than a fingerprint.

Therefore, in terms of details, fingerprint collection is finer than footprint collection, and it is more difficult and detailed.

Liu Guodong is not a novice in this area, of course there is no problem.

"I just hope that the other party will be more careless. It would be best not to wear gloves..."

Of course, Lu Chuan also hoped that the other party was not wearing gloves, but this possibility was unlikely.

The murderer was very thoughtful, and he could think of erasing the drag marks, and would not leave fingerprints without wearing gloves when killing people.

Security room on the first floor.

Sun Jun's monitoring and access is not going well.

"The monitor has been broken for a week and has not been fixed."

There is no monitoring, and the flow of people in the building is so large, how to investigate?

"In this way, when I first entered the apartment, didn't I see that all the owners in the building had to swipe their cards to enter? Can you export the card swiping records of all personnel from last night to 8:[-] this morning?"

"This is no problem, wait for me for a while, and I can get it out right away."

The door of Haizhou International Apartment uses a magnetic card access system, and each magnetic card is bound to a room.

Although some cards may be directly used by the owner to the tenant, they cannot directly lock the identity of the person, but after locking the house, it is enough to check.

Soon, Sun Jun's group got the relevant data.

"Let's divide into groups. There are 180 and [-] people in total. We will work in groups of two. Make sure to find out the basic information of all the personnel today."

This kind of thing is basically no different from finding a needle in a haystack.

No one knows whether the person who killed Zhou Yang was the owner or the tenant here.

Is it possible that an outsider did it? The security of the building is not watertight.

Don't swipe the card, skip the gate directly, and the security guard doesn't care.

But this is the way to solve a case. After investigation, there is no guarantee that there will be clues.

But if you don't check, there must be no clues.

Zhou Yang's parents also came to the single apartment where Zhou Yang lived.

Zhang Hui was learning about Zhou Yang's situation with the two of them.

"Mr. Zhou, what friends does Zhou Yang usually have and who is he close to? Can you tell me?"

A photo of Zhou Yang's parents sitting on the sofa with their son in their arms.

Tears... have long since dried up. (end of this chapter)