Question 4: Other Methods of Identification

Methods of Victim Identification

1. Fingerprinting

2. Facial Reconstruction

3. Dental Implant Record

1. Fingerprint

2 types of fingerprint :

1.      Digital Fringerprint

2.      DNA Fingerprints

Digital Fingerprint

1.      come from the raised ridges of skin that runs in patterns of curving lines along the tips of fingers and thumbs

2.      the common patterns includes arches, loops and whorls

3.      do not change throughout the course of life

4.      unique to every individual except for identical twins

5.      divided into 2 types : patent fingerprint and latent fingerprint

Patent Fingerprint

 friction ridge impressions which are obvious to the human eye and which have been caused by the transfer of foreign material from a finger onto a surface.

Patent prints can be left on surfaces by materials such as ink, dirt or blood.

Latent Fingerprint

accidental impression left by friction ridge skin on a surface, regardless of whether it is visible or invisible at the time of deposition.

Latent prints may exhibit only a small portion of the surface of a finger and this may be smudged, distorted, overlapped by other prints from the same or from different individuals, or any or all of these in combination. For this reason, latent prints usually present an “inevitable source of error in making comparisons,” as they generally “contain less clarity, less content, and less undistorted information than a fingerprint taken under controlled conditions, and much, much less detail compared to the actual patterns of ridges and grooves of a finger

DNA Fingerprinting

-          also known as DNA profiling

-          99.9% difference in every individual except for monozygotic twins

-          Embedded in every cell, blood, sweat and saliva

 

HOW

1.      Collection of samples (blood, sweat, tears, body fluids) from crime scene and samples from suspects

2.      Polymearase Chain Reaction (PCR) method used to create unlimited copies of the obtained samples in a short time to increase the amount of DNA available for Restriction Fragment Length Polymorphism (RFLP) testing.

3.      RFLP a sequence of DNA that has a restriction site on each end with a "target" sequence in between. A target sequence is any segment of DNA that bind to a probe by forming complementary base pairs. A probe is a sequence of single-stranded DNA that has been tagged with radioactivity or an enzyme so that the probe can be detected. When a probe base pairs to its target, the investigator can detect this binding and know where the target sequence is since the probe is detectable. RFLP produces a series of bands when a Southern Blot is performed with a particular combination of restriction enzyme and probe sequence.

2. Facial Reconstruction 

This method is often used as a last resort to identify the skeletal remains of an unidentified person, and it suffers from an ongoing skepticism caused by the advent of the personal computer and modern software technology. There are numerous techniques to sculpture a face onto the skull, all of which rely on the reproduction of a potentially recognizable face using the published soft tissue thicknesses in different racial groups .Facial reconstruction is a method used in forensic anthropology to aid in the identification of skeletal remains. The reproduction of the facial features of an individual is based upon the average soft tissue thicknesses over various anatomical sites of the skull and jaws and is duplicated by means of modeling clay. There are significant differences in the thicknesses of the soft tissues of males and females of different races Various techniques have been employed to measure the thickness of the facial tissues of adults, children, and young adults . The methods used to "flesh out" a face may vary, but each method incorporates a harmonious balance between science and art that eventually results in a reproduction of a face that may lead to an identification.

However experienced the sculptor is, there are certain accuracy limits that occur during the reconstruction of a face. Sculptors can only guess hairstyles and cannot create the expressions on a persons face that make the sculpture completely life like. However, a sculpture is successful if it aids in jogging someone's memory or can narrow down a search by excluding anyone whose face does not resemble the reconstructed face.

HOW

The Steps:

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.

3. Dental Implant Record

A dental implant is a prosthetic device that is inserted into the upper or lower jawbone, onto which an artificial tooth, crown or bridge can be anchored. Dental implants are typically constructed from titanium. More recently some manufacturers are constructing their implants from zirconia or a combination of titanium and zirconia.

The physical properties of high corrosion resistance, high structural strength and high melting point, suggest the retention of intact implants following most physical assaults. As the implants are machine made, they lack the individualisation required for their use as identifiers of the deceased, however the Straumann™ Company (Waldenburg, Switzerland) has recently released information that within the chamber of their implants they have laser etched batch numbers. 

Dental implants made from titanium have a melting point greater than 1650ºC and those made from zirconia have a melting point greater than 1850ºC. This physical property of extremely  high melting point could potentially assist in the identification of victims where there is lack of other scientific evidence such as DNA or fingerprints and loss of the fragile dental remains. 

In the cases of extreme incineration of victims who have been treated with implants it is important to ascertain if the implant batch or serial numbers within the implant chambers survive the incineration process sufficiently that their numbers can be identified.