Chapter 455: Skeletal Identification
The preservation time of skeletons is closely related to the surrounding environment.
Human bodies, lacking protective skin or fur, can begin to noticeably decompose after about a week in a hot, humid environment.
Typically, a body exposed outdoors for about a month will have its skin and muscles fully decomposed, leaving only the fascia.
In about two months, the body will become skeletal; human bones exposed outside can last for at least a year, but under suitable conditions, they generally decompose completely within five years, leaving no trace.
Bodies buried underground decompose more slowly than those on the surface.
This is because lacking oxygen below ground reduces the activity of aerobic bacteria, slowing decomposition.
The specific decomposition time depends on the soil’s moisture and temperature.
Generally, a body buried underground will completely skeletonize after one to three years.
There are exceptions, such as when humidity is very high, preventing full decomposition of the body.
Even after a long time, three, five, or even over ten years, the body might not fully skeletonize.
The soil humidity and temperature beneath the Lion Mountain Bridge are relatively normal, so bodies stored for about a year will become skeletal, and after 20 years, smaller bones completely disappear, leaving only larger ones.
Besides sturdy, large bones such as thigh bones, shin bones, hip bones, and skulls, other bones have become fragile.
As for the phalanges and tarsal bones, there is hardly anything left.
This bone excavation took longer than the time since Wang Mingshan’s body was found yesterday.
Lu Chuan and Old Bai worked for four or five hours, only finishing the cleanup of the 20-year-long skeletal remains just before dawn.
No one else was idle; Wang Changjiang and Shen Yan were urgently gathered at the scene to manage and classify other skeletal remains, with more transport work to follow.
Seven skeletons...
It will take more than a day or two to analyze and identify them all.
All skeletons were transported back to the Criminal Investigation Team by 10:30 a.m.
In the forensic autopsy room.
Lu Chuan, yawning, discussed with Wang Changjiang how to proceed with the work.
The analysis of Wang Mingshan’s bones is complete; his identity and skeletal features have been confirmed, and a corresponding analysis report has been finalized.
The remaining bones mainly need to have their identities confirmed.
Due to the large number of skeletons, the forensic team and crime scene investigators decided to work together.
"First, let’s collect DNA samples to see if we can identify these people through the DNA database."
Liu Guodong’s suggestion was valid.
Perhaps due to the long time elapsed, the clothes on these bodies have long decayed beyond recognition.
Two bodies had remnants of ID cards, but the text is blurred, and the cards themselves are nearly decomposed.
This suggests that the perpetrator did not attempt to conceal identities when committing the murder or burial.
For instance, Wang Mingshan’s police ID was found near his remains.
Collecting DNA samples from bones is much more complicated than ordinary DNA sample collection.
Theoretically, DNA typing can be performed on any nucleated cell.
However, extracting DNA samples from skeletal remains is a long-standing challenge in DNA analysis.
The hardest part is extracting the DNA sample from bones, and even then, testing methods are not uniform.
Currently, the more mature detection and extraction methods include mitochondrial DNA testing, STR testing, and NGS testing.
Based on Lu Chuan’s current skills in intermediate crime scene investigation, there is a higher success rate of extracting DNA samples from long bones like tibias, fibulas, and femurs.
Extracting DNA samples from smaller bones like the phalanges and carpals is much more challenging.
In forensic anthropology, when bones are discovered, the first step is to identify the species of the bones.
Just like when bloodstains are found, the first step is to determine whether it’s blood, and then if it is, whether it is human or animal blood.
With bones, once you determine the material is bones, you then identify whether they are human or animal bones through analysis.
Similar cases were encountered by Haizhou City’s Criminal Investigation Team more than a decade ago. The suspect burned the body after murdering, leaving behind bones mixed with those of cattle, sheep, and chickens.
Due to the time elapsed, identifying such bones can be quite challenging.
Most people assume human bones are distinct from other animals, but this is not always the case.
A segment of a human phalanx and a pig’s hoof bone can be indistinguishable to the untrained eye regarding whether it’s animal or human bone.
While everyone can recognize flesh on bones, bare bones are different...
Even professionals like Wang Changjiang and Shen Yan aren’t necessarily well acquainted with human bones.
In criminal investigation, there is a specialized field for Bone Identification Analysis.
Such incidents are rare in forensic cases, which explains the specialization.
Once a plan was set, everyone got busy; Liu Guodong, Old Bai, and Yang Sen worked on sanding and cutting bone samples.
Lu Chuan gave sequential numbers to the seven skeletons and then identified and analyzed them individually.
"Skeleton 1, male, aged between 38 to 43, height about 1.8 meters, upper left jaw... had two dental implants."
Skeleton Identification Analysis can be difficult or easy, depending on one’s grasp of techniques and cues.
With Lu Chuan’s current skills, he could discern basic details about a skeleton owner within about ten minutes of touching and observing it.
The reason for touch is that the feel and texture vary by age, gender, and even profession.
"Skeleton 2, female, aged between 42 to 46, height about 1.65 meters, no childbirth history."
This assessment caught the attention of Wang Changjiang and Shen Yan, as having no childbirth history at 42 to 46 was unusual.
"These two skeletons were found in one burial site; I suspect they may have known each other in life or shared a close relationship, such as being spouses."
"Brother Bai, later check if any couple disappeared around eight years ago."