Diary of a Criminal Investigator-Chapter 329: Unexpected

In the entire apartment building, more than three hundred people reside.

These individuals were investigated by Qinzhou City’s Criminal Investigation Team within a week after the incident.

Particular attention was paid to single males who were questioned in person.

Now, Wang Song’s suggestion has narrowed the focus further to individuals with a history of lewd behavior or voyeurism.

However, such private tendencies might not be caught before, so how should they be judged?

The old method: it’s still like searching for a needle in a haystack.

The special task force doesn’t have a Forensic Doctor, but they do recognize the autopsy report from Qinzhou City’s Criminal Investigation Team.

The cause of death of the victim is very clear, as are the signs of assault.

Meanwhile, the body is currently preserved in the morgue and can be re-examined at any time.

On the top floor of the apartment, Wang Song inspected the layout of the entire apartment once more.

During the time of the incident, all four elevators in the apartment were operating normally, and the surveillance cameras installed inside also had no malfunctions.

The Qinzhou Criminal Investigation Team has retrieved the surveillance video from that time; thirty-two people used the elevator to enter the apartment around the time of the incident.

"Captain Qin Hui, could someone get me the videos from half an hour before and after the incident?"

"Sure, I’ll arrange that."

Wang Song firmly believes that the perpetrator is likely a repeat offender. He has encountered such suspects before.

Usually, suspects of sexual crimes exhibit certain distinctive behaviors in their gaze or body language when observing attractive individuals.

This involves the psychological analysis of why someone would commit such an assault.

The main reason is the lack of desire control.

No one would willingly commit a crime, looking at the punishment of the aftermath.

However, the suspect still commits the crime, especially in crimes fueled by desire, like assault. The person lacks self-control and foolishly believes they can escape legal consequences, which emboldens them to commit the crime.

Soon, the video was handed over to Wang Song.

His partner was precisely Song Mingguang.

"Captain Song, shall we watch it together?"

"Sure, let’s watch it together."

Song Mingguang agreed with Wang Song’s perspective, but even if the suspect exhibits distinctive behavior when observing others, it shouldn’t be easily noticeable.

This is about keen observation skills; coincidentally, both Song Mingguang and Wang Song believed they possessed such skills.

Of course, finding a person in the video involves some level of probability.

After all, besides the elevators, there are also stairs in the apartment. The stairs are not monitored, so if the perpetrator left via the stairs, the elevator’s surveillance wouldn’t capture anything.

Qinzhou City’s Criminal Investigation Team, Crime Scene Investigation Laboratory.

Lu Chuan was preparing the Footprint Identification and Analysis work, creating a model.

The perpetrator left footprints at the scene, wearing the victim’s shoes, which made the footprints left abnormal compared to normal footprints.

Creating a model helps Lu Chuan obtain more accurate analytical data.

Now, during the model’s drying process, Lu Chuan is measuring some surrounding data of the blood droplets collected at the scene.

Bloodstain collection mostly employs two methods in general.

Since the bloodstains at the site had dried and changed color, Lu Chuan used a scalpel to scrape off the bloodstains this time.

If the bloodstains were still wet, methods like using cotton swabs, gauze, or glass slides could be applied for extraction.

The perpetrator wiped the floor mainly to remove the shoe prints, so the bloodstains on corners, walls, and furniture weren’t meticulously wiped.

A lot of spatter and drip patterns remained.

Lu Chuan collected these to analyze the height comparison between the perpetrator and the victim by measuring the bloodstain data.

The victim, Wang Min, was 165 cm tall, and during the assault by the perpetrator, the blood spattering was influenced by numerous factors.

For instance, height comparison of the perpetrator and the victim, the force of the weapon, angle, and so on.

Similarly, from the drip patterns, based on the "tail" length of the droplets, the victim’s speed and direction can be determined.

This work has also been conducted by the City Public Security Bureau in Qinzhou.

However, compared to the data Lu Chuan gathered himself, there’s still much room for improvement in accuracy...

"Height... 175 to 178 cm... very forceful, not very old..."

The Bloodstain Pattern Analysis gave Lu Chuan a rough profile of the perpetrator.

Young, physically fit, with strong muscles, capable of easily overpowering the victim.

After two hours, Lu Chuan basically completed the Bloodstain Pattern Analysis.

The Crime Scene Investigation personnel in Qinzhou City’s Criminal Investigation Team are also quite adept at bloodstain analysis.

It’s not exceptionally brilliant, but at least it’s systematic. Lu Chuan is familiar with Wang Ruiqing and feels their skill level is similar to Yang Sen’s.

The crime scene reconstruction based on their Bloodstain Pattern Analysis is fairly accurate.

The re-enactment of the perpetrator entering the room, assaulting, and slashing corroborates the actual situation at the scene accurately.

However, there’s a significant gap concerning the Body Data Judgement of suspects based on bloodstain characteristics.

With the Bloodstain Pattern Analysis complete, the shoe print model Lu Chuan initially made is also mostly finished and ready to use.

In many crime scenes, to mislead the police, the perpetrator intentionally wears shoes one size larger when committing the crime.

There are also cases where the perpetrator wears slightly smaller shoes.

But regardless of whether the shoes are larger or smaller, the footprints left behind can be identified and analyzed by a real footprint expert.

However, shoe and foot size disparity results in differentiated footprint characteristics, making the identification analysis relatively difficult.

Shoes one size larger leave more blurred shoe print edges, presenting roughly a one to two-millimeter data difference compared to standard shoe prints.

Of course, this depends on how much larger the shoes are; usually, one size larger yields about a one to two-millimeter blurred edge.

Conversely, in smaller shoes, the focus is on determining the center of gravity.

Typically, the foot’s center of gravity is in the middle of the foot, and in people with a normal arch, the foot’s center of gravity is practically suspended.

However, measurements can be made between the ball of the foot and the heel.

When in smaller shoes, the toes are more deformed compared to the heel.

Small shoes lead to curling or compressive deformity of the toes, shifting the foot’s center of gravity.

Lu Chuan is currently measuring this data, then performing a certain restoration to determine the suspect’s information.

The female footprints found at the scene have been confirmed by Qinzhou City’s Criminal Investigation Team to belong to the victim.

The shoe size is a 38.

This shoe size generally means that a man with slightly larger feet can only barely insert the front half of the foot and can’t fully wear it.

In such a case, the footprint’s center of gravity should be located near the front of the heel.

However...

Lu Chuan already measured both sides, finding that the footprint’s center of gravity is not near the front of the heel as initially determined by Lu Chuan, but rather centrally and slightly forward.

Additionally, the blur data around the shoe print doesn’t indicate large feet in small shoes but rather small feet in large shoes!

"No, that’s not right!"