Chapter 288: The Tiny Details

Reconstructing the crime scene is essentially imagining the crime myself.

In simple terms, I imagine how I entered the scene—through the front door, the roof, a window, the floor, or even like a medieval assassin, launching an upward strike from beneath the outhouse.

The method of entry can be imagined, the movements inside the scene can be simulated, and the same applies to the exit route and location.

With sufficient blood for trace analysis, Jiang Yuan could reconstruct the scene with exceptional precision, because blood simultaneously reveals the positions, speeds, and accelerations of both the killer and the victim.

To be honest, bloodstain pattern analysis is sometimes more useful than installing several detectors on the suspect's body, even more specific and authentic than footage from surveillance cameras.

Of course, this is the ideal scenario.

Most criminal investigators can only manage the entry and exit points; the middle part—the actual act of violence, the specific motions, the sequence of killing—is rarely addressed in detail, and that part is usually left to the forensic pathologist. Well, ultimately, it still falls to Jiang Yuan.

As for this scene, there's little blood, so the clues are minimal.

But for Jiang Yuan, even this small amount of blood reveals much: the killer's trajectory—he likely entered through the door and accelerated within two or three steps, striking the cashier directly with a blow, then striking again.

Judging from these two decisive actions, the killer was extremely decisive, likely aware the place held money, possibly even planning this for a long time. Jiang Yuan followed the direction of the blood spatter—the killer probably gathered the money while still holding the weapon and continued forward…

Ahead was the window.

Jiang Yuan stood still, tilting his head to ask He Guohua: "How did you determine the killer's trajectory? Where did he come from, and where did he go?" He Guohua, already bored, heard this basic question and assumed Jiang Yuan was just asking casually: "He came in through the front door, killed the cashier, took the money, and ran out?"

His tone was uncertain. That was natural—there were few clear signs in the room indicating the killer's path.

Whether in crime scene investigation or bloodstain analysis, everyone's skill levels were clearly uneven.

Jiang Yuan no longer teased. He said directly: "The killer jumped out the window."

"Ah?" He Guohua froze, took two steps forward, then suddenly turned and went back to the door to fetch several transparent acrylic stools, placing them near the window before standing at the window to look down.

"Is this footprint the killer's landing mark?" He Guohua felt a small surge of excitement.

The problem wasn't the absence of footprints—it was the sheer number, making identification impossible. If they could confirm even one footprint as the killer's, it would be a major breakthrough.

Wang Bo, the former high-dimensional being, wasn't swayed by He Guohua's excitement. He asked with independent thought: "Master, shouldn't we first determine why the killer jumped out the window?"

"Jiang Ye already said he jumped out the window!" He Guohua glared at his apprentice, then leaned out: "Look at that footprint below—doesn't it look like a jump? Would a normal person jump from the second floor?" The first-floor window could also be an exit…

The first-floor window has steel bars welded across it—when I told you to pay attention to details, what exactly were you looking at?

He Guohua immediately scolded his apprentice.

Wang Bo had wanted to challenge Jiang Yuan, but his professional skills weren't developed yet—he was instantly crushed by He Guohua's authority. Wang Bo tried to argue again: "But Jiang the forensic expert didn't even look down…"

"Doesn't that prove how brilliant Jiang Ye is?" He Guohua was now fully in online mode, eyeing Wang Bo like an enemy keyboard warrior.

Wang Bo shrank his neck and muttered: "He didn't take the normal path, and no one noticed—why didn't he just use the door?"

This was the core difficulty. He Guohua turned to Jiang Yuan. Jiang Yuan shrugged: "I can't explain it yet, but based on the scene's traces, that's exactly what happened."

If we speculate, there could be many reasons:

The killer might be a parkour enthusiast who avoids normal paths; or he got excited and jumped directly; or he intended to confuse the investigation; or there might have been more than one killer, and someone decided to double-cross the others…

Jiang Yuan had no evidence to support any theory yet, and he didn't want to speculate on it now.

His goal was to solve the case, not to convince young amateurs like Wang Bo—if they became too troublesome, he'd just replace them. He Guohua, by contrast, was much more obedient and immediately followed Jiang Yuan's line of thought: "So we can assume the killer is young. Broaden it a bit—people in their late thirties or forties generally wouldn't choose jumping out a window."

"Age is probably around thirty." Jiang Yuan walked to the window, looked down at the footprints, made a judgment, and said: "Collect the footprints below first, then come back up to find matching ones."

The footprints downstairs were made by the jump—they were quite clear. The floor above showed no visible prints, but once collected, traces would remain, though they might require instruments to detect.

Thinking of Jiang Yuan's footprint identification ability, He Guohua's hope blazed up—he grabbed the investigation kit and left.

Footprints should be collected as quickly as possible, especially outdoor ones—a single wind or rainstorm could erase them.

Modern homicide cases are relatively easier to solve partly because killers generally prefer committing crimes indoors; statistically, the most common crime scene is the perpetrator's own home.

This creates a situation where criminal traces are extremely hard to eliminate. Bloodstains left indoors may persist for ten years. How different from outdoors, where traces vanish within weeks or months.

Of course, the main reason for this choice is the sheer number of surveillance cameras outside.

Changyang City has a professional electrostatic lifting device for footprint extraction—a device the size of a palm, with a few dials. He Guohua went downstairs, took several photos of the footprint, then set the device aside and pulled out a sheet of insulating paper, laying it over the print.

The insulating paper was black, somewhat like old carbon paper.

It was naturally charged with static electricity, trembling and irregular.

After placing the insulating paper, He Guohua pressed the two corners of the electrostatic device onto it—one end grounded—and turned on the switch. The paper immediately adhered to the ground.

"Roller." He Guohua extended his hand. His apprentice immediately handed it to him.

He Guohua held the roller and gently rolled it over the insulating paper, explaining to his apprentice: "Just flatten it—don't use too much force; we'll use adhesive next."

"Got it."

Wang Bo nodded.

He Guohua returned the roller to his apprentice, then carefully peeled off the insulating paper. He glanced at it under the light—the footprint was clearly replicated on the paper.

He Guohua stored the insulating paper in a box to process later in the lab.

Then he took out the adhesive.

The adhesive was a black adhesive sheet, standard A4 size, resembling a sticky mouse trap, its surface pitch-black.

Using the adhesive was simpler: just lay it over the footprint, roll it once with the roller, press it down with your hands, then peel it up.

However, after using the adhesive, the original footprint on the ground was destroyed—that's why electrostatic lifting must come before adhesive.

Back upstairs at the crime scene, He Guohua turned on the forensic light and adjusted the illumination to scan the floor for footprints.

Even footprints invisible to the naked eye became crystal clear under the forensic light.

Forensic lights are adjustable in wavelength—if you can't see it, you can tweak the wavelength, but white light usually suffices.

He Guohua continued collecting the footprints.

When he looked up, he saw Jiang Yuan staring blankly at the window.

"Jiang Ge—"

"Done scanning," He Guohua reported.

"Hmm… Did you scan the window frame? Any fingerprints?" Jiang Yuan gestured with his hand.

The window frame was plastic—fingerprint collection was inherently difficult. He Guohua smiled: "We got some fingerprints, but we don't know if they're the killer's."

"Then let's collect again." Jiang Yuan took the investigation kit and began brushing.

He Guohua hesitated: "Do you think the killer touched the window frame?"

"Try simulating it—holding the weapon in one hand, jumping out the window—can you avoid touching the frame?" Jiang Yuan demonstrated. He Guohua mimicked it, muttering: "Actually… you can't."

Wang Bo whispered: "I can stand two meters from the window, jump hard, lift both feet off the ground, pass through the window, and land on both feet…" Wang Bo not only described it—he moved his body, swinging his feet on the wooden bridge without tilting.

He Guohua sighed at Jiang Yuan: "He minored in gymnastics. National first-class athlete."

Jiang Yuan could only grunt: "So competitive… If he's national first-class, send him to get printer toner."

"Huh… Okay. For brushing fingerprints?" He Guohua asked, but didn't wait for an answer—he sent Wang Bo off immediately.

In an instant, Wang Bo was sprinting under the sunlight.

Jiang Yuan nodded: "With this plastic material, fingerprints often can't be lifted—mixing printer toner with magnetic powder works better."

As Jiang Yuan explained this small technique, He Guohua quickly wrote it down—crime scene investigation is all about detail; the real test lies precisely in these tiny things.