Chapter 533 Footprint Analysis (Please Vote for This Big Chapter!)

The technical leader continued to report.

On the projection, there are three groups of shoe prints that have been separated.

"After comparison, it can be determined that two of the two groups belong to the victim Li Yansong's day shift taxi driver."

The two sets of shoe prints on the projection disappeared, leaving only the left set of shoe prints.

"The extraction of shoe prints on the foot pads is sequential. We used existing technology to extract a total of seven shoe prints on the foot pads."

"After separation, six layers of shoe prints were successfully extracted."

"Among the first four shoe prints, the first is that of the day shift driver Chen Qiang, and the second is that of the victim Li Yansong."

"The third layer belongs to Chen Qiang, the fourth layer belongs to Li Yansong, but the fifth layer belongs to this set of unfamiliar footprints, and the sixth layer belongs to Li Yansong."

"The sixth shoe print can be determined to be the last set of shoe prints left after Li Yansong was murdered."

"Then going back, the fifth level is the unfamiliar shoe print. It should be the shoe print left by the murderer after driving for a short time!"

Chen Yan and Wang Fenglei stared at the shoe prints on the projection, looking a little excited.

So far, this is the only evidence left by the killer.

“Compare now in the ex-convict database!”

"yes!"

No fingerprints were found, but the shoe prints finally did not disappoint.

Moreover, for Chen Yan, this set of shoe prints is more than just a set of simple comparison data.

There is a system reward for specializing in trace identification skills. Chen Yan's understanding of shoe prints is beyond the reach of others.

In Chen Yan's previous life, there was actually a specialized professional police force in the police station, namely footprint analysts.

There are very few such talents, but every one of them is very powerful and precious.

General footprint analysts can determine the weight, walking habits and other basic information of the owner of the shoe prints based on the shoe prints.

Some powerful footprint analysts can not only determine this basic information, but can even know the murderer's professional characteristics and determine the gender, height, age and other information.

This will be of great help in solving the case.

Chen Yan’s Trace Firm skill specialization has a reserve of knowledge in this area.

"Team Wang, help me arrange a room and be quiet. I want to conduct footprint identification and analysis on this set of footprints."

Footprint identification analysis?

Wang Fenglei was slightly startled: "Chen Yan, do you still understand this?"

"I know a little bit about it. In this case, Team Wang, our provincial team should have talents in this field. You can ask them to do the appraisal together."

"If you integrate this with my identification, you will probably get more information."

The Liao Provincial Detective Brigade naturally has talents in this field, but it is hard to say to what extent they can achieve it.

In particular, it is difficult to determine the unclear footprints peeled off by multiple footprints.

Furthermore, the set of footprints of the murderer were left in a sitting position, so the analysis and judgment of a lot of information are inaccurate.

For example, the simplest weight.

Shoe prints left by a sitting position are completely different from shoe prints left by a standing position.

On the other hand, it also has something to do with the shoes you wear.

But since Chen Yan said this, it means that he must be certain.

"Okay, I'll make arrangements right now!"

Chen Yan nodded.

Chen Yan knows the difficulty of footprint analysis better than Wang Fenglei.

But other than this, there are currently no other clues.

No fingerprints were left, analysis of the soil was not yet available, and investigation of the video was inconclusive.

Now, there is only this set of footprints.

Ten minutes later, Chen Yan was already sitting in a quiet office.

On the desktop, there are more than a dozen photos of footprints from different angles.

Front, side, front and back, etc.

However, not every photo is clear.

At some angles, there is even only half a photo.

The photos here are all proportionally restored based on the actual size of the shoe prints. Chen Yan is measuring them with a ruler at the moment.

Generally speaking, it is easy for everyone to understand how to judge the owner's weight through footprints.

The deeper the footprint, the greater the weight.

The footprints are shallow and the weight is definitely lighter.

In fact, in real footprint analysis, the depth of the footprints is not very important.

Because the footprints left by the same person are different on different ground surfaces.

In trace analysis, the most important footprint size is.

The clarity of footprints in different parts.

Use these to judge basic information.

For example, the clarity of the footprints in the arch of the foot.

Under the same conditions, the shallower the footprints on the arch of the foot are, it means that the owner has a higher arch.

In most cases, excluding the interference of diseases such as flat feet, the height of the arch of the foot can determine the proportional relationship between weight and height.

The size of the footprints in the arch of the foot can determine the size of the arch bones.

From these, the owner's height range, weight range can be calculated.

This is how footprint analysis works.

This is why Chen Yan kept using a ruler to measure the data in different directions of the footprints.

Time passes bit by bit.

Each group is advancing its own work.

Liu Qingshan’s side had the largest number of people.

More than 300 detectives spread out in the self-built housing area on Fenghuang Street, looking for cameras from house to house.

Although there are only two alley entrances into the self-built housing area from surveillance camera No. 36 on Phoenix Street to surveillance camera No. 37, no one can guarantee that taxis will drive in this area after entering the alley entrance.

Therefore, the entire Fenghuangshan Street self-built housing area must be included in the scope of the investigation.

There are more than 17,000 households here.

Three hundred people sounded like a lot. On average, each detective would have to check about fifty households before they could all be lined up.

Of course, not all the more than 17,000 households have been investigated in place. Detectives only focus on investigating households with cameras outside their houses.

After one night, I had a clear understanding of the basic situation.

3298 households!

In the entire area, 3,298 households have installed various cameras.

Here, there are relatively few people who have made peace with their families.

The main reason is that there are more shops along the street in the self-built housing area.

About 80% of them are cameras installed in shops.

At noon on the second day after the incident, all detectives completed copies of the video materials they searched.

However, the most troublesome work comes next.

That is watching videos.

Video material between 3:08 and 4:30 yesterday morning.

3298 households, one and a half hours of video for each household...

That adds up to more than 3,000 hours of video...

Liu Qingshan asked the Shen City Detective Team to apply specifically for the right to use the expo center.

More than 300 people gathered here to watch the video.

Why focus? It’s to increase everyone’s attention.

If viewed separately, there is no atmosphere and it is easy to miss important information.

The most critical thing may be the fleeting one-second picture in the surveillance.

There are more than 300 people, and each person is assigned ten videos.

After reading it all, the results will be available in ten and a half hours.

At this time, there are two supplies that everyone urgently needs.

Instant noodles and eye drops.

After the case analysis meeting ended yesterday, these people left and haven't eaten yet.

Of course, you can't work hungry, eat first and then talk.

Then there are eye drops, two bottles per person.

At this time, the importance of the Sky Eye system is highlighted.

This is just a surveillance video of a self-built housing area. What about the entire Shen City?

If there was no Sky Eye system, let alone other things, the video of the last appearance of Li Yansong's taxi on Phoenix Street would be found in a timely manner, and the entire Shen City Detective Team would be involved. It would probably not be possible in a month or two.

And just when everyone was full and ready to start, everyone received a message.

While paying attention to taxis, look for a man between 1.68 and 1.7 meters tall, thin and about fifty years old.

The most distinctive feature of the man is that he is slightly lame in his left foot.

From the moment he got the photos of the shoe prints at around 11 o'clock last night until noon today, Chen Yan didn't rest for more than ten hours.

The characteristics of the suspect given to Liu Qingshan were the result of Chen Yan's more than ten hours of work.

Yes, Chen Yan's analysis of the suspect's footprints has yielded very good results.

The first thing Chen Yan determined was the height range of the suspect.

The determination of footprint analysis requires a breakthrough point.

Generally speaking, height and weight are the most important fixed analysis points in footprint analysis.

As long as one type can be determined more accurately, the other information can be calculated based on the data measurement of the shoe print.

The first thing Chen Yan determined was the height of the suspect.

This is determined based on the length of the arch of the shoe print and the adjustment angle of the taxi driver's seat.

Based on the size and angle of the arch bones, it is indeed possible to infer the owner's height, but without other references, it is very difficult and the error is relatively large.

The reason is that the accuracy of measurement and the clarity of shoe prints, as well as the shoe prints left by different shoes, will also cause errors.

According to the texture of the shoe prints at the scene, it can be analyzed that the shoes worn by the suspect are sports shoes.

Compared with leather shoes, these shoes leave clearer shoe prints and reflect more accurate data.

But because the ratio between the length of the arch bone and the height is very strict, if the difference is just one millimeter, the height will change by several centimeters.

Moreover, although the footprints left by sports shoes are relatively clear, they are still compared to leather shoes.

It's still different from real footprints.

Therefore, there is an error in the measurement.

But combined with the angle of the suspect's adjustment of the driver's seat, Chen Yan was able to judge the suspect's height relatively accurately.

The height of the deceased Li Yansong was 1.75 meters, but after the murderer adjusted the seat, Li Yansong's knees actually hit the console under the steering wheel.

This shows that the suspect must be shorter than Li Yansong.

Taken together, it should be under 1.7 meters.

Judging from the foot arch measurement data, the murderer's height was at least about 1.68 meters.

Therefore, taken together, it can be determined more accurately that the height of the deceased was between 1.68 and 1.7 meters.

This data should be said to be very accurate.

Combined with the height and the measurement data of the shoe prints, it can be determined that the murderer is thin, about 60 kilograms.

As for gender, it is best to determine.

There are certain differences in the structure of the feet of men and women.

This results in the construction of men's shoes and women's shoes being somewhat different.

The gender of the murderer can be determined by the style of shoes.

As for age, this is analyzed from the focus of different parts of the shoe print.

The gaps between the bones of the human foot continue to expand with age.

As you age, the gaps between bones will become larger, which will lead to different pressure densities transmitted from the foot to the shoes.

Although the soles are flat, the shoe prints formed after being stressed are still slightly different.

The traces should be deeper when applying force on bones, and shallower when applying force on gaps.

Based on these judgments, the proportion range of bone gaps can be determined.

In this case, the age range can be inferred.

Chen Yan gave a judgment of about fifty years old.

But the fluctuation range is relatively large, it may be more than 40 years old, or it may be nearly 60 years old.

However, considering that the murderer started committing crimes fifteen years ago, if he was forty years old, he was only in his twenties fifteen years ago. At this age, it is difficult to have a stable mentality, cruel methods and such disregard for life.

As for those who are sixty years old, their physical strength will be severely reduced, and they will kill people...

Therefore, Chen Yan's comprehensive age is about fifty years old.

Of course, it would be very difficult to find someone with these basic characteristics.

Most of the self-built houses on Fenghuang Street are rented by migrant workers. Among these people, middle-aged men in their fifties account for a large proportion.

Moreover, since they are migrant workers, few of them are particularly well-nourished, and most of them are relatively thin.

So trying to find someone based on this characteristic is like looking for a needle in a haystack.

Fortunately, when Chen Yan analyzed the shoe prints, he discovered something interesting.

The distance between the arches of the left and right feet in the two shoe prints is actually not equal.

This is unlikely.

Although normal people will have one foot larger and one smaller, the difference is very subtle, and it is almost indistinguishable when it comes to the difference in bones.

Most people leave symmetrical shoe prints on their left and right feet.

However, among the footprints left by the suspect, the arch of the left foot was obviously longer.

Starting from the middle part and continuing to the back heel, it seems to be the arch of the foot, with no obvious focus point.

Something is wrong.

It is impossible for normal people's feet to leave such footprints.

Unless the owner of the shoe print has a disabled left foot and uses an inner height increase.

In this case, such shoe prints will be left.

It is difficult to find a thin middle-aged man in his fifties, but if there is a lameness, it will be different.

As soon as Chen Yan completed the footprint analysis, he sent the results to Wang Fenglei.

"Male, 1.68 to 1.7 meters tall, thin, lame, about 50 years old..."

When Wang Fenglei got the analysis results of Chen Yan's footprints, he was completely stunned.

Just a pair of shoe prints...

How the hell could you analyze so many things?

At this time, the technician responsible for footprint analysis at the brigade also handed over the results to Wang Fenglei.

Not only was it handed in, it was several hours earlier than Chen Yan.

"Male, height between 1.6 and 1.8 meters, weight between 55 kilograms and 80 kilograms."

Comparing it with Chen Yan's analysis results, Wang Fenglei wanted to throw away the other report.

In the conference room, Wang Fenglei took the report and looked at Chen Yan with some disbelief: "Chen Yan... How confident is this analysis?"

"Gender is definitely no problem. The height error will not exceed five centimeters, the age error will be plus or minus five years, and the weight error will be about ten kilograms. However, lameness should not be a problem."

Chen Yan gave the above answer in the affirmative.

"In this case……"

Wang Fenglei's eyes gleamed.

"He...can't run away!"

Chen Yan also breathed a sigh of relief at this moment.

With such an accurate portrait, it is indeed difficult for the opponent to escape.

Especially the discovery of the clue of lameness greatly increases the probability of solving the case.

Although the murderer was very cunning, he planned the entire crime process in detail before committing the crime, and he must have been able to escape the scene of the crime so quickly and without any flaws after visiting the scene many times.

However, precisely because of the other party's caution, he is likely to leave evidence in the surveillance near Phoenix Street.

Judging from the current situation, Li Yansong's taxi disappeared after passing by the surveillance camera at No. 36 Fenghuang Street, which means that the murderer most likely got into the car between camera No. 36 and camera No. 37.

Then he directed Li Yansong to turn into the alley entrance of the self-built housing area.

After that, the other party directed all the way and avoided all the cameras, so that Li Yansong's taxi disappeared.

The premise is that the murderer must have stepped nearby.

By checking on the spots, we deliberately selected unmonitored routes.

After checking the locations, the murderer picked out an unmonitored route, but in the process of checking the locations, the murderer would definitely leave clues!