Diary of a Criminal Investigator

Footprint Identification and Analysis, ideally, involves analyzing and identifying footprints on soft surfaces like sandy or muddy grounds.

Footprints left on such soft carriers are clear and three-dimensional, allowing for a more accurate analysis of the physical characteristics of the footprint owner.

In reality, however, such clear footprints at crime scenes are only possible in outdoor crime scenes.

At indoor crime scenes, most floors are made of boards, tiles, or cement, with few soft surfaces, so the clarity of the footprints might be enough, but they lack a strong three-dimensional effect.

Even more challenging is when the criminal disguises their actual footprint features by altering their normal shoe size.

Lu Chuan had encountered various types of footprints before, but today was the first time experiencing a non-footprint footprint.

The suspect used stilts to hide their footprints, making it impossible for the average person to deduce the suspect’s physical characteristics from such traces.

Theoretically, the stilts used by the suspect would leave trace outlines on the ground that differ in size due to different force directions and walking postures.

This variation, through complex mechanical calculations, could roughly estimate the suspect’s weight.

Lu Chuan was now performing this calculation.

However, besides weight, other physical traits, like height, age, or even professional traits, were extremely difficult to determine, as the killer had masked these very well.

Crime Scene Investigation isn’t superhuman; it’s impossible to revisit the crime scene as it happened, relying only on the traces on-site for some analysis.

Lu Chuan’s footprint identification analysis couldn’t achieve the same results as a normal footprint analysis from a mere speck.

Of course, solving cases doesn’t just depend on Lu Chuan alone.

With the suspect’s occupational characteristics provided by Lu Chuan, the High-tech Zone Criminal Investigation Team acted very quickly.

Moreover, there are very few people engaged in magic or juggling work, and the relevant personnel was pinpointed within just two hours by the next morning.

"Gao Feng, male, twenty-one, an apprentice at Red Star Circus, resides in the unit building where the victim lives, renting an apartment on the ninth floor."

Gao Feng?

He is the only person in the community engaged in this kind of work.

"Boss, should we make an arrest?"

Yuan Shaokang initially intended to give the order immediately but hesitated and called Lu Chuan: "Lu Chuan, how’s your analysis coming along?"

"The Footprint Identification and Analysis results are out; the suspect’s weight is approximately between fifty to sixty kilograms. The micro-trace analysis will take about another hour at most."

An hour?

Yuan Shaokang ultimately decided to wait, figuring the suspect wouldn’t flee, opting for caution, and to await Lu Chuan’s micro-trace analysis results before making a move.

In the Micro-trace Evidence Analysis laboratory, Lu Chuan was conducting the final data analysis.

Micro-trace analysis doesn’t always yield valuable results.

For instance, some micro substances collected from the theft site by Lu Chuan, such as dust and food residues, lack specificity and are difficult to use as evidence or clues to advance the case.

Purity extraction in micro-trace identification is particularly troublesome. Some other Criminal Investigation Teams, like the one in Tianzhou City, have separate posts for Crime Scene Investigation and Trace Inspection.

The benefit of having separate posts is that criminal investigators can specialize further, with Crime Scene Investigation officers focusing solely on-site tasks and not on subsequent data experiments.

They also focus exclusively on the evidence analysis sent by Crime Scene Investigators without engaging in reasoning or on-site work.

This specialization accelerates skill development.

But this segregation can lead to each department working solely for their own purposes.

For example, Crime Scene Investigators might collect as many items as possible from the scene, pushing everything onto Trace Inspectors for examination.

Ideally, Trace Inspectors prefer the items provided by Crime Scene Investigators to be as refined as possible, not mixed in a collection bag with several or more different types of evidence.

Micro-trace analysis, in particular, demands higher single-item inspection specificity.

Lu Chuan devoted substantial time to purification, the most challenging and time-consuming process.

Diligence paid off, and the final result revealed that the debris left by the marks was oak.

"Captain Yuan, oak is generally more often planted in the south; it’s rarely seen here in Haizhou City."

"Also, if you discover items made of oak in the suspect’s home, bring them in for testing. Even among oak trees, each has slight compositional differences."

Lu Chuan’s findings gave Yuan Shaokang confidence; the association with Gao Feng was currently more hypothesis than certainty.

Indeed, no fingerprints, footprints, or any crucial evidence were left by the suspect at the crime scene.

It couldn’t just be claimed that the high-strength gel used to open the door is something magicians often use, or that the site’s presumed stilt marks relate to jugglers, leading to the conclusion that the only juggling apprentice in the building was the suspect.

If arrested, what if the suspect denies it, or demands evidence from the police?

As for the stolen cash...

Even if placed before the police, it doesn’t constitute evidence, as it wouldn’t respond when summoned.

Lost jewelry is much easier to deal with; if Gao Feng had already gotten rid of it or hid it elsewhere, it’s simply impossible to find.

But with Lu Chuan’s micro-trace analysis results, things were different.

If the stilt could be found in the suspect’s house and identified to match the micro-trace results from the crime scene, Gao Feng wouldn’t be able to escape.

"Haha, Lu Chuan, thank you, thanks to you this time. We’re going to make an arrest now, and I’ll treat you to a meal later!"

The case wasn’t large but was quite time-consuming; Lu Chuan pulled an all-nighter, something not often seen even in some murder investigations.

After Liu Guodong finished his morning meeting, he also learned of Lu Chuan’s assistance in solving the case.

"Did Old Yuan’s case get solved?"

"Yes," Lu Chuan replied, lighting a cigarette for Liu Guodong and pouring a cup of tea. "They just caught him; the stolen necklace and ring have been recovered. The Red Star Circus apprentice was doing clown makeup at home when caught..."

The suspect believed his actions were flawless, not promptly disposing of the stolen goods, which were left on the coffee table when apprehended.

This also simplified things for Lu Chuan, eliminating the need for further identification.