Modus operandi. [Part 2 Question 5]

Question 5      :  

• List the evidences that have been presented to both the doctors.

• Considering the evidences available up to this point in time, describe in detail how you would go about investigating further, assuming you are Dr. Rudi or Dr. Suria, explaining what you anticipate at each step.

The evidence that have been presented to both the doctors are:

1. Adult’s skull & jaw

2. Pieces of a jaw

3.Child’s jaw

Considering all the evidence brought up at this point, we have determined how we would like to tackle the challenge of identifying the victim by :

1. First determining the age by tooth eruption
2. Identify the victim through dental records
3. DNA cross-referencing with missing people list
4. As a last resort, facial reconstruction with 3D facial mapping

The first and most obvious step is to look and observe the skull and mandible given.

What is the first thing that catches your eye??



To us budding detecteeth,we find most interest in the tooth still present on the mandible.

But, what can we learn from the remaining tooth that can aid in our investigation?

Well, believe it or not, dentist can make an accurate guess of a person’s age by looking at their dentition especially with regards to the primary dentition. Although this method is relatively accurate and cost-free, it is effective mostly in determining child and adolescent victims.

By analysing the dates of different teeth, calcification, root formation and resorption of deciduous roots can help to establish the age of a dead person for identification and living person to establish whether the person is juvenile or adult.

**FUN FACT: Dental age determined by eruption dates can be as accurate as ±1.5 years!

We can categorise dental age into 3 phases:

1- ageing in prenatal, neonatal & early postnatal (in utero)

2- age estimation in children & adolescents

3- age estimation in adults

With regards to our case, we are interested in the 2^nd and 3^rd point.

The first evidence shows an adult skull and a complete mandible which is pretty straightforward. Since the mandible is not broken off, we can deduce that the second evidence which is only pieces of a jaw belongs to another individual. 

In the second evidence, there are only pieces of a jaw.
We can clearly see the 3 teeth on the mandible, by :

Deduction: The mandible belongs to an adult victim
Explanation: 3rd molars are only present in people of at least 17 years old.

In the 3rd evidence, we can see a child's jaw covered in black dirt or soot which makes it harder to identify the age of the child just by looking. One way to extract more information would be to take a radiograph of the child's jaw to see the calcification, root formation and resorption of deciduous roots and determine the estimated age of the child using this handy table as reference.

So, we now know that we are dealing with 2 adult victim and a child victim.
But, we cannot accurately determine the victims with just their age.
Which brings us to our next strategy:

2. Identify the victim through dental records

Teeth enamel is the hardest substance in the human body, which can withstand temperature of more than 2000 degrees! So it will remain intact for identification purpose even after other body parts are gone. Firstly, the list of missing persons in and beyond the area is retrieved from the police department. Then, after analysing the teeth remains, the missing persons whose age are out the range are crossed out from the list. Next, dental record in the physical form or electronically (Open Dent) must be obtained from the remaining missing person’s dentist. Through examination and comparison, the missing person will be identified as tooth arrangement and fillings and other dental work are unique to the individual

3. Mitochondrial DNA profiling

Hhmm...why mitochondrial DNA?
Why not use nuclear DNA instead?

Since we are looking at a highly decomposed corpse, it is better to obtain mitochondrial DNA because it is more resilient compared to nuclear DNA, hence making it possible for it to be extracted from highly degraded samples.

As soon as the victim's mitochondrial DNA is extracted from the remains, HV1 & HV2 regions are amplified using Polymerase Chain Reaction method (PCR). The next step would be sequencing the mitochondrial DNA to create a DNA profile so that it can be entered into a computerized DNA database.

Yes, in case you are wondering, there is a DNA database which contains each individual's DNA including yours and mine!

These information entered into the DNA database will be cross referenced with the Missing Persons Database or Unidentified Persons Database and voilà.... the victim can be identified!

4. Facial Reconstruction with 3D Facial Mapping

So…what if all we’d gotten so far are negative results?! How disappointed must you be feeling right now! Fret not because we have yet to utilize our last resort!

As our avid reader, you must have read that there’s an incredibly amazing technique that allows us to reconstruct one’s facial outlooks. Yes, you’ve guessed it correctly and it is indeed the 3D Facial Mapping!
 

Now that we’ve reconstructed the face of our victim, we can try to make a positive identification or to jog the memories of the public who may have been witness to something around the time of the victim’s disappearance or death. Who knows, maybe this can get us another step closer to the underlying truth…

Reference:
1. www.srmuniv.ac.in/sites/default/files/files/Forensic.pdf
2. http://etd.lsu.edu/docs/available/etd-0331103-130706/unrestricted/McClanahan_thesis.pdf