Chapter 8: Chapter Eight: Comparing Fingerprint Whorls

The old desktop computer hummed and rattled as it operated.

Hot air whooshed out from the case, dispersing into the air.

After a while, twenty fingerprint matches with the highest similarity scores appeared on the right side of the LCD screen.

Jiang Yuan wasn’t in a hurry; he sipped his tea, then opened the first fingerprint to examine it.

Over the past two days, the criminal investigation team had been operating at full capacity due to Uncle Seventeen’s murder case, but now it had suddenly eased up, and Jiang Yuan had returned to his usual forensic routine—lacking any real work.

Meanwhile, he was gradually becoming proficient in using his newly acquired system reward: “Chongqing Single-Fingerprint Analysis Method—Arch Pattern Identification (Lv3).”

After practicing with old school exercise books and publicly available data, Jiang Yuan decided to move to real-world application: first find an arch pattern, then identify whose fingerprint it was.

As his first step, he chose a fingerprint collected from a robbery case in Longli County, a neighboring city.

He avoided murder case fingerprints because, under the “must-solve-all-murders” policy, murder cases received top priority and abundant resources; fingerprints were thoroughly cross-referenced before becoming cold cases. Fingerprints still lingering in the database from unsolved murders were inevitably extremely difficult.

If Longli County had an unsolved murder case with a suspect’s fingerprint extracted, that fingerprint would first be repeatedly matched by local forensic officers; if no match was found, they would return to the scene multiple times to attempt re-collection; if all attempts failed, they would certainly request assistance from the municipal criminal science and technology team—or even directly approach the provincial bureau.

If even the provincial bureau failed to match it and the case remained unsolved, every one or two years, the provincial bureau or even the ministry would organize special fingerprint campaigns to re-match fingerprints from major cold cases, involving experts from the provincial or ministerial criminal technology talent pools or youth talent pools.

Jiang Yuan had already eaten Lv3 fried rice with egg, so his expectations for Lv3 arch pattern identification were modest.

Fried rice with egg was delicious, but it didn’t glow.

Thus, Lv3 arch pattern identification was powerful, but not godlike.

Especially since the fingerprint databases he could access were restricted; challenging a murder case with his first fingerprint match would be too likely to crush his confidence.

In comparison, robbery cases were more suitable for now.

On one hand, ordinary robbery cases didn’t reach the level of provincial major cases; on the other hand, robbery cases were sufficiently prioritized at the county level, meaning the forensic officers who collected the fingerprints had been thorough. The fingerprints uploaded to the database were sufficiently linked to the case.

Even so, when Jiang Yuan first opened the fingerprint image from this case, he was quite surprised.

It was unclear under what conditions the fingerprint had been collected—it was blurry and incomplete, only about half the size of a normal fingerprint. Fortunately, the fingertip area was mostly preserved, providing a basis for comparison.

Besides that, the fingerprint was distorted, of course.

This situation was entirely different from fingerprints left by ordinary people clocking in for work. Without professional expertise, not only could you not mark characteristic points, you’d struggle even to determine which finger it was.

The system’s automatically matched twenty fingerprints, as expected, all failed to match.

Jiang Yuan wasn’t discouraged; this fingerprint had been uploaded precisely because local forensic officers had struggled to match it. The failure could be due to technical limitations or simply because the corresponding fingerprint wasn’t in the database.

If it was the latter, Jiang Yuan could do nothing but hope his own bureau’s fingerprint database was broader… but right now, he was betting on the former.

For forensic officers doing fingerprint matching, effort was mandatory—only through effort could they earn a chance at luck.

Jiang Yuan closed the fingerprint comparison page and reopened the suspect’s fingerprint image, this time using Photoshop.

He carefully observed the state of the incomplete fingerprint, then began adjusting contrast and brightness.

Jiang Yuan adjusted with extreme precision; it took him half an hour just to slightly enhance the fingerprint image’s clarity.

But sharpening the tool doesn’t delay the chopping; after all preparations were complete, when Jiang Yuan carefully examined the fingerprint again, the ridge patterns became much clearer.

Next, Jiang Yuan slightly adjusted the fingerprint’s central point.

Because the fingerprint was severely incomplete, the central point itself was uncertain; if Jiang Yuan didn’t adjust it, the system would automatically estimate one.

Jiang Yuan studied the ridge patterns, repositioned the central point, then returned it to the software, modified the parameters, and clicked confirm again.

Another twenty fingerprints—no match.

Slight adjustment of the central point, then compare again…

This time, Jiang Yuan immediately spotted the third-ranked fingerprint.

To an ordinary person, fingerprints all look roughly the same at first glance, especially when they’re all arch patterns or loop patterns—it’s often extremely difficult to distinguish them.

But for someone who’s stared at fingerprints for a long time, different fingerprint features are like freckles on an old sow’s face—the longer you look, the more familiar they become.

Jiang Yuan directly opened the third fingerprint, enlarged it, and placed it on the right side of the screen; then he opened the original fingerprint and placed it on the left.

When the two fingerprints were placed side by side, their similarities became unmistakable.

At this point, it wasn’t just about spotting characteristic points—it was about directly judging overall similarity. In a one-to-one comparison, the human eye’s discernment far surpassed the computer’s.

“Matched!” Jiang Yuan murmured to himself, feeling a wave of relief, and casually submitted the matched fingerprint.

According to procedure, his submission would go to provincial experts for review; once they confirmed it was correct and clicked submit, someone would notify the relevant frontline unit, which would then arrange the arrest themselves.

Of course, the local criminal investigation team could also make the arrest without waiting.

Jiang Yuan didn’t care anymore; he stretched, stood up to loosen his muscles, checked the time, and settled in to wait for quitting time.

A forensic pathologist’s life without corpses was simple and pure.