Diary of a Criminal Investigator

Qin Hui, Wu Qiming, Wang Ruiqing, and others from the Qinzhou City Criminal Investigation Team didn't sleep the entire night.

On the edge of the ruins of the Minghe Bridge, Li Donglin supervised the battle all night.

With leaders from the provincial department overseeing the work, all resources were delivered to the scene immediately.

Emergency lighting vehicles lit the entire site as if it were daytime.

More than thirty firefighters worked in shifts, using small handheld demolition hammers, chiseling away at the bridge pier's concrete. After nearly twenty hours, at dawn the next day, they finally cleared out all the skeletal remains.

However, no one felt the excitement of completing the work; instead, everyone's heart sank to the bottom.

In the first pier, four sets of skeletal remains were excavated.

In the second pier, three sets of skeletal remains were uncovered.

A bridge over a hundred meters long, with thirteen piers, yielded seven sets of skeletal remains!

The early spring air was still cold, chilling everyone to the bone.

"Seal off the scene, and send the bones back to the team."

Qinzhou City Criminal Investigation Team, Forensic Laboratory.

Lu Chuan and others had a bit of sleep last night and now felt relatively refreshed.

However, faced with seven sets of skeletal remains, their expressions were unsightly.

Not to mention who these people were, or how they died, just the fact that there were seven of them!

How could there have been no news back then?

How is that possible?

The skeletons were fully excavated, and the most important task now was to confirm their identities.

First, the cause of death needed to be determined.

"Skeleton number one, the fourth left rib has a laceration from a sharp object; the cause of death is preliminarily judged to be a sharp object piercing the heart…"

"No cement residue was found in the cranial cavity of skeleton number one, indicating it was poured into the cement pier posthumously."

"Skeleton number two, right leg has a comminuted fracture; left arm has a dislocated fracture; the third and fourth ribs on the left side are fractured, and the seventh rib on the right shows fracture traces."

"Hyoid bone fracture, death by asphyxiation…"

"Skeleton number three has a skull fracture; neck is broken; the sixth left rib has a cracked fracture, and the left leg's tibia has a dislocated fracture."

"Skeleton number four has a percussion fracture mark on the right arm…"

The students following Zhang Yuanchao may be called students, but their forensic capability surpassed that of many grassroots units' forensic doctors.

The theoretical knowledge for complex skeleton identification analysis was there, though practical experience was somewhat lacking.

However, in terms of ordinary skeletal injury identification, these individuals had no issues.

Each set of remains exhibited injuries, from which the cause of death could largely be directly inferred.

For instance, a fracture of the hyoid bone typically becomes a separate entity once a body is skeletonized.

Without external destruction, fractures are unlikely.

Thus, generally speaking, discovering a fractured hyoid bone among skeletal remains is a strong indicator of asphyxiation death.

The other bodies also showed clear skeletal injuries.

The seven bodies could be clearly determined from the skeletal injuries to have suffered varying degrees of abuse or harm before death.

This largely ruled out accidental death and the possibility of concealing a body.

Additionally, in three cases, the cement was poured around them while they were still alive.

The other four were only entombed in cement after their vital signs ceased.

The most important task for the forensic doctors and crime scene investigators is now to use technical means to determine the victims' identities.

The cause of death is basically confirmed. DNA extraction from the bones is handled by Zhang Yuanchao's student, while Lu Chuan is responsible for determining the precise time of death for the seven bodies.

The time it takes for a body to skeletonize varies greatly depending on environmental conditions.

In high-temperature, high-humidity natural environments, without external factors like animal scavenging, skeletalization can occur in as little as half a month.

For example, in tropical rainforests, after a person dies, decomposition begins within a day before rigor mortis has fully subsided.

After three days, complete bloating occurs.

After a week, the muscles decay and dissolve, leaving only the skin covering the body.

By ten to fifteen days, maggots digest the body completely, leaving only grey-black bones.

During weathering, the grey-black bones gradually turn snow-white.

Generally, the whiter the bones, the longer the time of death.

But relying on color alone to determine the time of skeletalization is inaccurate.

Lu Chuan needed to conduct some experiments.

The concrete used for bridge piers differs from regular concrete.

Concrete has many grades, applied to different settings based on project nature.

Cement grading refers to its strength index, measuring solidification strength after mixing and hardening.

Many factors influence cement strength, such as mineral components in the cement, particle size, and the temperature and humidity during hardening.

The cement for the Minghe Bridge piers was low-temperature Portland cement, which offers better resistance to water compared to regular Portland cement.

The bodies were sealed during the cement pouring process.

Fifteen years later, inside, the bodies have completed skeletalization, but determining specific time of death remains challenging, especially for the four already deceased when sealed.

The experiment is quite simple: Lu Chuan wrapped a chicken leg in cloth, using cement identical to that back then for sealing.

Then by adding certain chemicals, he simulated the changes of fifteen years.

This simulation relies entirely on experience, including what substances to add and in what quantities to mimic fifteen years' passage accurately.

While the crime scene team was busy, frontline detectives from the Qinzhou City Criminal Investigation Team remained occupied.

The company that won the construction bid for the Minghe Bridge was the First Bridge Construction Group of Qinzhou City; its subordinate highway bridge construction company was the contractor.

The Minghe Bridge was then a key project in Qinzhou City, with comprehensive related documentation.

Fifteen years is a long time, but not enough for everything to change.

Those responsible for the project back then were arrested one by one.

Workers who handled the concrete pouring were also being sought, especially the focus was on them.

After completing the concrete pouring, vibration is required, especially for bridge pier construction, which demands no construction flaws.

After care, professional quality inspection is required.

So how did they pass inspection when bodies were encased in the piers?

Was the worker responsible for vibrating one of the culprits?

It's considered one of the culprits because there were seven victims, and pouring the pier's concrete couldn't be interrupted.

This means the four bodies in one pier and the three in another were at least poured simultaneously.

This would be impossible for one person to achieve.

As the construction continued, multiple job types needed to collaborate.

Arrest and interrogation processes proceeded simultaneously.