The amalgamation of artistry with forensic science, osteology, anatomy, and anthropology to recreate an individual’s face from its skeletal remains is known as Forensic Facial reconstruction.
There are two types of forensic methods of facial reconstruction:
a. 2D Reconstruction (Sketching & Computerised)
b. 3D Reconstruction (Claying & Computerised)
Forensic facial reconstruction is a method used in the field of forensic science to reproduce the likeness of an individual from skeletal remains, primarily used in cases of missing or unidentified persons.
It is a technique used to aid in building an “alive” face out of skeletal remains and the reproduction of facial features is based upon the soft tissue thicknesses over the underlying bony structure of the skull.
The use of facial reconstruction in forensic science to produce an image from a skull offers a sufficient likeness of the living individual.
The image will facilitate the identification of skeletal remains by stimulating memories of relatives, friends, or witnesses. The skull provides clues to personal appearance.
The brow ridge, the distance between the eye orbits (sockets), the shape of the nasal chamber, the shape and projection of the nasal bones, the chin's form, and the overall profile of the facial bones all influence facial features in life.
Using these bones, artists and forensic anthropologists work together to reconstruct facial appearance through the process of forensic facial reconstruction using clay (the Manchester technique).
21 Osteometric markers are usually applied to the face. It allows researchers to make comparative measurements of the skull in a unified and unambiguous manner.
The values of each point were determined by numerous studies of tissue morphology in living and deceased persons from a range of ancestral groups.
A trained sculptor, who is familiar with facial anatomy, works with a forensic anthropologist and uses clay to build the facial features.
The forensic anthropologist interprets skeletal features such as the subject's age, sex, and ancestry, and anatomical characteristics such as facial asymmetry, evidence of injuries, and loss of teeth before death.
Therefore, facial reconstruction is an exacting process. The finished product approximates the actual appearance because the skull does not reflect the details of soft tissues, eyes, hair, skin color; facial hair; the shape of the lips; or how much tissue fat covers the bone.
History of Facial Reconstruction
Facial reconstruction - making faces - is an old story.
In ancient Egypt, great efforts were made by scientists to preserve as many details of their ancestors as they could. In 1953, the excavations made in Jericho brought to light the first examples of facial reconstruction.
Plaster skulls with shells into eye-sockets to simulate eyes were found under the floor of houses aged about 7500-5500 BC (the Pre-Pottery Neolithic).
Reproduction of facial features from Cranial remains was first done by Welcker in 1883 & His in 1895. He used soft tissues for facial reconstruction. Later, Gerasimov’s techniques were used by his students to help in criminal investigations in 1964.
Meanwhile, in 1946, the American anatomist Wilton M. Krogman popularized Facial reconstruction & formulated 5 general principles to standardize methodology in reproducing the unpredictable soft tissues of the facial features, which defined the relation of the eyeball to the orbit, the shape of the tip of the nose, the location of the ear, the width of the mouth, and the ear length.
In 1981, Caldwell assured the value of 3-dimensional reconstructions through a questionnaire.
Russian palaeontologist, Professor Michail Gerasimov is known as the father of the technique of facial reconstruction, in 1924, he developed the “Russian method” in which the development of the musculature of the skull and neck is regarded as being of fundamental importance.
Methods of Facial Reconstruction
The reconstruction techniques can be divided into two types:
- Two dimensional (2D)
- Three-dimensional (3D)
They are carried out and analyzed either manually or by using specific software (computerized).
The 3D manual methods used in forensic facial reconstruction are the Anatomical (Russian), Anthropometrical (American), and Combination Manchester (British) methods which were developed by Gerasimov, Krogman, and Neave respectively.
Two-dimensional Reconstruction
This is used to recreate a face from the skull with the use of soft tissue depth estimates.
This method was first developed by Karen Taylor in Austin, Texas during the 1980s.
This method requires an artist and a forensic anthropologist to work together on facial reconstruction and is based on antemortem photographs and the skull which is to be reconstructed. This method is also used in the identification of the deceased from skeletal remains.
Three-Dimensional Manual Reconstruction
This method also needs both an artist and a forensic anthropologist. In manual methods, facial reconstruction is done by using clay, plastic, or wax directly on the victim’s skull or more often a replica of the skull which has to be identified.
This method is similar to two-dimensional methods as it also requires the use of tissue depth markers of specified lengths to represent different soft tissue depths.
The markers are inserted into small holes on the skull cast at specific strategic points or landmarks. In the computerized method, computer software produces reconstruction by using scanned and stock photographs.
Methods of Manual 3D Reconstruction
1. Anthropometerical American Method/ Tissue Depth Method: This was developed by Krogman in 1946. Through this method, soft tissue depth data is considered. This method was commonly used for reconstruction by law enforcement agencies.
Fine measurements were obtained by the use of needles, X-rays, or ultrasound. As facial muscles are recorded in a proper anatomical manner, this method requires highly trained personnel, so this technique is not preferred nowadays.
2. Anatomical Russian Method: This method was developed by Gerasimov in 1971. Here soft tissue depth data was not considered but facial muscles were used in anatomical position.
In this method, reconstruction was done by shaping muscles, glands, and cartilage onto the skull layer by layer. This technique is not commonly used these days.
This method is much slower than the American method and a greater degree of anatomical knowledge is required. Reconstruction of fossilized skulls has been achieved by this method.
3. Combination Manchester Method/ British Method: This method was developed by Neave in 1977 and is the most accepted method for facial reconstruction today.
In this technique, both soft tissue thickness and facial muscles are taken into consideration. Once the cranium and mandible are articulated and the skull is mounted on an adjustable stand in the Frankfort Horizontal plane, facial tissue pegs or markers.
Each peg length represents the mean tissue depth at the anatomical point. The facial tissue depth is determined by the age, gender, build, etc. of the individual.
The shape and size of various muscles are determined based on the underlying hard tissues. Plaster or prosthetic plastic eyeballs of 25mm diameter are placed into the orbits.
The prosthetic eyeballs are positioned in the orbit in such a way so that a tangent taken from the mid supraorbital margin to the mid infraorbital margins touches the iris.
The inner canthus are placed 2mm lateral to the lacrimal crest and the outer canthus are placed 4mm medial to the malar tubercle.
When the malar tubercles are absent, the outer canthus is placed 10mm below the line of frontozygomatic suture and 5-7mm from the orbital margin.
The maximum width of the nose is determined by the bony nasal aperture at its widest point as three-fifths of the overall width of the soft nose.
The profile of the nose and the shape and the size of the alae are determined by the nasal aperture. The maxillary canine and first premolar are placed near the corners of the mouth and the width of the mouth corresponds to six anterior teeth.
The thickness of lips is determined by upper and lower anterior teeth. The length of the ear is predicted by the length of the nose and the ear canal is positioned by using the external auditory meatus as the reference point.
Muscles of the face are usually modelled on the skull which is to be reconstructed in clay one by one, then a layer of clay is added over the musculature to represent the skin, subcutaneous fats and strips of clay are then rolled, shaped, and added over the muscle/fat structure to create the finished face.
4. Computerized 3D Forensic Facial Reconstruction: With the advancement in 3D technology, a fast, efficient, and cost-effective computer aided forensic facial reconstruction method was developed.
In this method, the operator used 3D computerized models using manual clay model techniques. Some computerized systems used 3D animation software (Free Form Modelling PlusTM; Sensable Technologies, Wilmington MA) to model the face onto the skull while other systems used a virtual sculpture system with Haptic feedback (Phantom DesktopTM Haptic Device; Sensable Technologies).
The haptic feedback system can feel the surface of the skull during analysis and also provides important skeletal details for facial reconstruction such as muscle attachment strength, the position of the eye, position of the malar tubercle, etc.
This system though requires both anthropological and computer modeling skills. It decreases the practitioner’s subjectivity and skill.
This method also creates multiple images of the same face quickly and efficiently. Nowadays, various computer software programs like CARESTM or CARES (Computer Assisted Recovery Enhancement System) and FACES (Forensic Anthropology Computer Enhancement System), etc quickly produce 2D reconstruction which can be edited and manipulated.
They work by capturing and digitalizing radiographs, photographs, and images of skulls and producing an electronically altered version of the image. These programs speed the reconstruction process and produce more generic images.
Conclusion
Forensic facial reconstruction is a rapid, non-invasive and efficient method where reconstruction can be repeated at any time if required. This technique is used in various cases- i.e, mass disasters, arson cases, buried & decomposed bodies, etc.
Visual identification by the individual’s family and associates thus becomes easy and more defined.
For the classical manual technique, various methods are used but the Combination Manchester Method was found to be the best and most accurate method for the identification of an individual.
The manual methods on the other hand are labor-intensive. Computerized forensic facial reconstruction can also mimic the manual method of facial reconstruction.
Computerized remodelling of missing individuals is also significantly easier as compared to the manual method and also decreases practitioner training.
October 17, 2022 - BY SIFS India