Most Brutal! Part II

Question 4

Besides dental aspects in obtaining evidences, we could also resort to fingerprint evidence, visual identification of victims by family members or close friends by looking at the deceased body or photograph of the face. 

But with regard to this case where all the soft tissues have decomposed, more suitable ways are:

(i)DNA Fingerprinting/ DNA Profiling

DNA profiles are encrypted sets of numbers that reflect a person's DNA makeup, which can also be used as the person's identifier.

Gel electrophoresis is used to separate the DNA fragments according to their size and charge. Negatively charged DNA will move towards the positive electrode. Heavier DNA fragments move slower than lighter ones.

Procedure of DNA Profiling:

1. DNA samples are taken and amplified using PCR. The samples can be taken from hair, bones, soft tissues, teeth, pulp etc. As we have mentioned in the last post, powdered dentine and cementum of human teeth remains unaltered without regard to the environmental condition.

2. Restriction enzymes cut DNA into fragments at specific base sequences in each sample. 

3.A fluorescent marker binds in a triplet in the DNA fragments so that results can be seen.

4. Samples are added to a gel electrophoresis chamber. Electric current is passed through pushing the fragments along. 

5. Heavier fragments stay closer to the origin and smaller fragments go further. 

6. Banding pattern shown up from the DNA sample will be used to compare against the suspected victim's. The pattern would be the same if it's from the same person. Banding pattern can be similar for closely related individuals, eg. parents and siblings.

What is PCR?

Polymerase chain reaction amplifies a small amount of DNA sample, like a tiny blood sample from a patient or crime scene, when a lot of DNA is needed for DNA profiling.

Here is a video that accurately and easily depicts how DNA fingerprinting is done.

McGraw-Hill.com

(ii) Forensic Geology

Forensic geologists compare, identify, analyze earth materials such as soils, rocks, minerals and fossils found at the crime scene and the victim's remains which could be traced to the location where the crime was committed and the point of disposal or release. In other words, this could be used to associate or dissociate a person or object with that location. In some cases, the comparison of earth materials or changes in materials is used to determine the time and incident occurred, the cause of an incident and responsibility for an incident.

According to this article: Forensic Geology Case Histories http://web.mst.edu/~rogersda/forensic_geology/Geoforensics%20Case%20Histories.htm, it is easy to conclude that soil is frequently collected as supplemental evidence. 

(iii) Forensic Facial Reconstruction

It is the process of recreating the face of an individual whose identity is often not known from their skeletal , , remains through an amalgamation (aka. union) of artistry forensic science, anthropology, osteology and anatomy. 

There are two major types of facial reconstruction:

(a) Two Dimensional Reconstruction

Markers will be placed on specific anthropological landmarks on the skull to estimate the tissue depth. Then a computer program is used to reconstruct the face of the victim. 

2D Facial Reconstruction

(b) Three Dimensional Reconstruction 

A replica of the skull is made from the cast of cranial remains, created by modelling clay or other materials. This is alike to taking an impression of a tooth. Or it could be a high-resolution 3D computer images.

3D Facial Reconstruction

Shall we go step by step now? :-D

1. Markers indicate the depths of tissue
   to be added to the skull (a cast in
   this case). Studies over the past century of males and females of 
   different ancestral groups determine
   the measures of these depths.
2. Applying strips of clay, the artist 
   begins to rebuild the face by filing in around the markers.
3. The artist begins to refine features around the artificial eyes.
4. The lips take shape.
5. Facial contours have been smoothed 
   and subtle details added to accurately personalize the reconstruction.

The finished product only approximates actual appearance because the cranium does not reflect soft-tissue details (eye, hair, and skin color; facial hair; the shape of the lips; or how much fat tissue covers the bone). Yet a facial reconstruction can put a name on an unidentified body in a modern forensic case—or, in an archaeological investigation, a face on history.

(All credits for the steps goes to

http://anthropology.si.edu/writteninbone/facial_reconstruction.html)

(iv) Radiocarbon dating

Our bodies naturally have carbon-14, and it is interesting to note that our teeth are carbon sponges: they absorb radioactive carbon readily. Once there, the level of carbon-14 barely changes. We absorb carbon-14 throughout our lifetime, and when we die our bodies lose C-14 at a fixed rate. Hence, this can be used to estimate the age and date of death of the victim.

Graph of C-14 Half Life

Question 5

Based on the pictures provided, we are able to identify:

1. Viscerocranium and a part of the neurocranium

2. The whole mandible bearing 5 teeth, namely 37,38, 46, 47, 48 (FDI numbering system)

3. A part of the skull that cannot be conclusively identified

4. Another adult jaw: the right half of the mandible, bearing 46,47,48.

5. A child's mandible with erupting permanent incisors. 

- Mental foramen is a stable landmark on the mandible. Mental foramen can be analysed as distances from mental foramen to lower border of mandible exhibit sexual differences.

- Cranial suture fusion sites can be used to estimate the anatomical age of the victim.

- Radiographs can also be taken to estimate the dental age of the victim.

To determine the identity of the child, DNA can be extracted from the mandible and teeth remains.

Any body tissue that has not been degraded is a potential source of  DNA.
	Bone is one of the best sources of DNA from decomposed human remains. Even after the flesh is decomposed, DNA can often be obtained from demineralized bone. DNA from bone has been used to identify the repatrioted bones from Vietnam era servicemen, and the remains of the White Russian Romanov family who were executed during the Bolsheviek revolution.
	Like bones, teeth can also be an excellent source of DNA, long after the rest of the body has decomposed.

To extract DNA, powdered form of bone or teeth remains is demineralised using EDTA(specific to these structures due to hydroxyapatite crystals). DNA is then extracted using silica extraction method. Purification of the DNA is done by binding to silica in the presence of high concentrations of guanidinium thiocyanate. Amount of extracted DNA is then amplified using PCR method. The DNA can now be used to carry out DNA fingerprinting.

The above procedure could also be done on the adult's skull remains. Before specimens of the skull or teeth are obtained to extract DNA, an impression of the skull could be taken to produce a replica for facial remodelling purposes. Hence the adult victim can be identified.

Most Brutal! Part I

Image 1

Image 2

Perhaps most people have heard of the notorious Ted Bundy, who was an American serial killer, who kidnapped, raped and was a necrophile. 

He was a savvy and intelligent murderer, who charmed his young female victims (mostly university students) to gain their trust, subsequently bringing them to a secluded location wherein he would overpower and assault them. He was smart enough to not leave evidence that could be used to link the crime back to him, eg fingerprints or the murder tool. It was by chance that his last victim Lisa Levy had a very distinguished bite mark on her left buttock and an officer laid a yellow ruler against the mark (left picture above). When Bundy became the primary suspect, a warrant was issued to get an impression of his bite (right picture above). A dentist Dr. Richard Souviron presented the findings to the judge, stating the teeth alignment, size of the teeth, sharpness of the bicuspids, lateral and incisor teeth, and the cuspal tip distance between adjacent teeth that were so unique to Ted Bundy’s dentition. Hence, the case was solved.

QUESTION 1

We have all heard of how Forensic Dentistry has helped in the identification of burnt victims and also victims with bite marks. Explain more about these and describe how is Forensic Dentistry could be useful in the identification of murder victims?

Forensic dentistry/ forensic odontology can also be used for the forensic analysis of burnt victims. Usually bones and teeth only disintegrate at temperatures of 855-1038 degrees Celsius. Since this is a very high range of temperature which can only be achieved in a special incinerator, most murdered victims' bones and teeth still remain of the charred body. So, forensic odontologists compile the dental chartings of the dentition, intra-oral photographs for (facial and dental comparison) and radiographs (showing the bone trabecular pattern, tori and osseous anomalies, natural and synthetic teeth, maxilla and frontal sinus configuration, presence of foreign bodies like implants and other prostheses), to piece the puzzle together to solve the mystery. Also, antigenicity of powdered dentine and cementum of human teeth remains unaltered without regard to the environmental condition – the main factor that affects the rate of decomposition of a body, for 1 – 6 months. According to The Internet Journal of Forensic Science CLICK THIS!,

the antigen is not only localized to the vascular network of the pulp, antigens can also be found on odontoblasts, dentinal fluid and at the periphery of the pulp.

It is interesting to also note that cheiloscopy (lip prints) and palatal rugae are unique to every individual, analogous to finger prints! J To find out more, just drop us a comment below! We love interacting with our readers!

QUESTION 2

Is a male human skull different from that of a female? If yes, how?

Forensic odontology is not as simple as it sounds. Among one of the reasons of the comprehensiveness of the subject is due to the difference in male and female skull structure.

Male                                                                                    Female                     

Here are the fast facts:

Weight:

·         Male: Heavier

·         Female: Lighter

Size:

·         Male: Larger

·         Female: Smaller

Bony mass or thickness of the bone:

·         Male: Thicker

·         Female: Thinner

Forehead

·         Male: Slightly sloping or receding

·         Female: Almost vertical

Cranial vault of the skull

·         Male: More rounded

·         Female: Flatter, less pronounced

Contour of the face

·         Male: Overall length of the skull is longer and the chin is bigger and protrudes more forward. Skull is uneven due to its muscular make up, and the zygomatic bones are more massive

·         Female: Skull is rounded, with facial bones being smoother, with both the jaws mandible and the maxilla being smaller

Supraorbital margin

·         Male: more rounded

·         Female: sharp

Tympanic plate

·         Male: larger and margins are rounded

·         Female: smaller and margins are less rounded

Frontal bone and forehead

·         Male: brow ridges are well demarcated

·         Female: smooth and more vertical frontal bone

Mastoid process

·         Male: larger

·         Female: Smaller

QUESTION 3

From the story above so far, how many victims are there? Explain.

It is not possible to conclude the number of victims yet as we have been provided with insufficient information. However if there is only one victim, there will only be one set of facial and cranial bones, of which we have to measure the dimensions of each part of the bones (eg frontal, parietal, temporal, occipital etc.) to reconstruct only one skull, and as well as one set of dentition. It could be a mixed dentition (there would be a mix of permanent and deciduous teeth in children, do not mistake this for two separate human beings!) hence the root and crown completion dates, and eruption dates of the teeth must be known and analysed to identify the age of the victim. Also, if the DNA could be extracted, there would only be one DNA profile.

If it is more than one victim, there would obviously more than one set of bones and dentition, and more than one DNA profile.

Having pitched this, further investigation is required to conclude the number of victims.