In recent years, the role of Crime Scene Investigation in the handling of various criminal cases has become increasingly significant.
From part-time work that any detective could dabble in a decade ago, it has now evolved into a specialized department.
Especially in city-level criminal investigation teams, most have established specialized Crime Scene Investigation teams, with forensic analysis often being handled by the same group.
This is the case with the Haizhou City Criminal Investigation Team, where Liu Guodong and his four-member team handle both field investigations and subsequent evidence analysis.
Of course, some more advanced teams have upwards of a dozen people in Crime Scene Investigation and another dozen in forensic analysis, which is typically only seen in provincial-level teams.
Footprints, as a common source of information extraction in crime scenes, have gradually developed into a specialized field of study.
However, whether at the Public Security University or frontline criminal investigation teams, there is a severe shortage of talent in this area.
The reasons are manifold; on one hand, the teaching is not systematic, on the other hand, some keep their skills to themselves, and yet another reason is the limited career advancement potential.
Even if someone is willing to teach, there may not be anyone willing to learn.
Compared to fingerprint identification, footprint analysis is relatively underdeveloped.
Therefore, Lu Chuan acquiring the skill of footprint analysis through the system is quite rare, despite it being only a basic level.
However, even at a basic level, while Lu Chuan might not grasp some aspects yet, it does not mean the system's rewarded skills are erroneous.
Footprint analysis involves many subtleties right from the measurements.
Firstly, there is the determination of the virtual edge, with a footprint's center of gravity typically focused on the ball of the foot.
However, because human feet have an arch, normally the middle of the footprint is the shallowest, while the ball and heel are the deepest.
From the center of the foot, the further out, the shallower the footprint, forming a virtual edge at the periphery.
The size of this virtual edge in shoes of the same size indicates the weight of the wearer.
The heavier the weight, the smaller the virtual edge.
By combining the length of the footprint, it is possible to calculate the height and weight of the footprint's owner.
However, in this case, the shoe prints left by the suspect have an irregular pattern in the front and back virtual edges, varying in size.
Although the difference is very subtle, it can still be measured.
Such a condition is likely due to the shoes worn being mismatched to the actual size.
Simultaneously, there are also differences in the left and right virtual edges of the footprint.
In other words, the suspect's shoes are not only longer than the actual size but also wider.
By further combining with the stride length and the depth of the footprint calculated at that moment indicating their weight, Lu Chuan determines the footprint owner is female.
However, she is wearing men's shoes, and they are a size too large.
No wonder the suspect couldn't be found; the gender was wrong, how could they catch the right person?!
Upon recalculating and confirming his judgment was correct, Lu Chuan continues to speculate on the suspect's physical features based on the footprint data.
"The inner edge of the footprint is slightly deeper, while the outer edge is lighter… The suspect has knock knees."
"Subtracting the virtual edge, the foot length is approximately 24.2 centimeters… thus the height is around 169 centimeters, and the weight is approximately 61 kilograms…"
An hour later, the suspect's characteristics have been thoroughly marked.
Female, 169 centimeters in height, 61 kilograms in weight, aged between thirty-two to thirty-seven, with knock knees.
"Ding"
"Basic task completed, host has utilized footprint analysis to deduce the suspect's physical characteristics in the robbery and assault case."
The moment Lu Chuan completes the calculation, the system's completion notification chimes.
Next, Lu Chuan opens another stack of documents, which consisted of all monitoring data from near the crime scene at the time.
During the robbery period, thirty-two people had their image information captured.
Of course, the suspect may not have passed through the monitored points where images were captured, which is merely a set of screening data.
Lu Chuan flips through the data, comparing each facial image.
Within a few minutes, Lu Chuan's gaze locks onto a woman named Zhang Yan!
"Hehe, it's you!"
Holding the woman's photograph, Lu Chuan locks up the crime scene storage room and leaves the Criminal Investigation Team directly.
"Old Yang, are you at the station?"
Unlike Lu Chuan who was assigned to the Criminal Investigation Team, Yang Lin was assigned to the police station after graduation, becoming a community police officer.
Coincidentally, the location where Zhang Yan resides falls within the precinct area that Yang Lin oversees.
Huaguang Street Police Station.
Yang Lin pours tea for Lu Chuan, taking Zhang Yan's information: "This person lives in a low-rent house, let me check the records."
Given their relationship, there's no need for formalities, Lu Chuan states his purpose directly: "This Zhang Yan is a suspect in a robbery and assault case from last year, can you see if you can collect her footprint, if they match, this cold case is solved."
"No problem, take a seat, I'll be right back."
Although the work in the police station is varied, it is relatively relaxed.
Generally, the cases handled by the police station are mostly neighborhood disputes or petty theft.
Any major criminal cases must be handed over, with the station generally only assisting in investigations.
Of course, this does not mean the station cannot investigate criminal cases; for cases not solved for a long time, the station can apply to take over.
Obviously, murders are out of the question, and no station would apply for a murder case.
Like Lu Chuan, Yang Lin is also professionally trained, so most tasks at the station are relatively simple for him.
In less than two minutes, Yang Lin returns with a stack of materials for Lu Chuan: "This Zhang Yan works at Anping Electronics Factory, single-handedly raising a daughter, and also caring for a paralyzed mother at home, she's one of our registered support targets."
Support target?
Lu Chuan did not expect Zhang Yan's family background to be so impoverished.
"I just contacted the electronics factory, Zhang Yan is still at work, should we go now or wait until she gets off?"
Quickly skimming the information, Lu Chuan thinks for a moment: "Let's go now, directly to the electronics factory."
Twenty minutes later, at Anping Electronics Factory.
The workshop supervisor leads Lu Chuan and Yang Lin to the workshop: "Officers, the person standing by the workstation, wearing blue overalls, is Zhang Yan."
"Let's collect the footprint first."
This part is simple, Lu Chuan brought a specialized footprint collection paper; standing on it briefly is all it takes to collect a footprint.
When Zhang Yan steps onto the paper, Lu Chuan closely observes her expression, noting her apparent nervousness, seeing her fingers tremble slightly, and her complexion pale.
With a silent sigh, Lu Chuan picks up the collected footprint, directly comparing it with the one found at the robbery crime scene.
Just like fingerprints, every person's footprint is unique.
If the two footprints match, it confirms Zhang Yan as the perpetrator.
"Officer… please… there's no need to compare… I'm the one…"
While Lu Chuan was in the midst of the comparison, Zhang Yan trembled as she confessed from behind.
Back at the Criminal Investigation Team.
Qin Yong stands in shock, listening to Liu Guodong who is reporting to him: "Say that again?"
Liu Guodong is also bewildered: "Lu Chuan just called, he said he caught the perpetrator of last year's robbery and assault case with the community officer at Huaguang Street Police Station."