The Effectiveness of Different Brushes in of Fingerprint Recovery Technique - Term Paper Example

THE EFFECTIVENESS OF DIFFERENT BRUSHES OF FINGERPRINT RECOVERY TECHNIQUE Name Course Tutor Date Introduction In the context of forensic science, fingerprints still remain the most important method of identification of individuals on a crime scene. The choice of fingerprints as the method of identification is based upon its ease and fastness in connecting a person of interest or suspect to a crime. There are numerous cases within the criminal justice system that depend on fingerprinting. Nearly all the cases use fingerprints from homicide, burglary, rape and robberies of all sorts not to mention its importance in solving civil disputes. As is with all tools used as evidence in courts of law, fingerprints are used to either exonerate the wrongfully accused persons or to convict the real perpetrators of a crime. Fingerprints are defined as the reproduction of ridge formations on a surface. The reasons why fingerprints are used for identification is because of three underlying principles; permanency, individuality, and uniqueness. The ridges are formed prior to birth and remain unaltered until otherwise destroyed through postmortem decomposition. As for individuality, two fingerprints can only be identical if produced from the same individual and from the same finger. Lastly, no two persons in the world can have the same fingerprints whatsoever. There are types of fingerprints at a crime scene include; patent or visible fingerprints, latent fingerprints and plastic fingerprints. Patent fingerprints are visible finger marks that are left when substances such as blood and ink gets in contact with the hands and is then transferred on a surface. Plastic fingerprints on the other hand refer to prints that are produced when the fingers get in contact with soft materials such as clay or putty. Latent fingerprints are the most common in a crime scene and form the best source of fingerprints for identification of individuals who could have been in a crime scene. Latent or invisible fingerprints are prints formed by the transfer of oils and other secretions from the body pores onto a surface. There are various methods of making a latent fingerprint visible these include optical, physical, and chemical methods. However, powdering is the most cost effective and efficient technique for enhancing latent fingerprints. History of Forensic Fingerprint Historical Context of Fingerprinting The use of fingerprints for identification purposes can be traced back to Asia and China in the annals of history (Lambourne, 1977). Sir William Herschel used fingerprints to authenticate deeds, contracts, warrants and payments in 1858 (Center for Applied Science and Technology, 2012). Paul-Jean Coulier suggested a method of developing latent prints and expounded on their reliability in identifying criminals. Later in the year 1880, Dr. Henry Faulds realized the importance of fingerprints stating that they were essential for the scientific identification of criminals (Lambourne, 1977). The basis of Henry Faulds was that friction ridges formed on hands are unique and could be classified based on a number of peculiar features to identify one fingerprint from another (Center for Applied Science and Technology, 2012). His proposition that fingerprints are permanent and unique formed the basis of use of fingerprints in the criminal justice systems as well as in most scientific research on the same. Sir Edward Henry developed a nomenclature classification system that could identify the prints from a crime scene and link it to a previous crime scene (Center for Applied Science and Technology, 2012; Lambourne, 1977). Henry’s ideas were coupled with Edmund Locard’s rules of using 12 points that match to make a valid conclusion that fingerprints are identical (Thomson & Tangen, 2013). The latter was adopted by various countries and there is literature available indicating some shift from it (Thomson & Tangen, 2013). Modern Day Fingerprinting The modern day forensic fingerprinting is founded upon the previous developmental approaches that were postulated and tested by various individuals. With the advent of technology, it must be accepted that there are challenges in fingerprinting (Beresford et al, 2012). However, it still remains the most important aspect of individualization. The individualization is based on various classifications such as the ZIMOX and Henry’s Classifications (Center for Applied Science and Technology, 2012). The friction ridges can be classified in terms f the patterns formed. Loops, arches and whorls together with their sub tenets or sub-classes, form the major patterns that are formed by the friction ridges in different individuals (Thomson & Tangen, 2013). There are characteristics of these patterns that are used in individualization; this includes ridge endings, bifurcations, islands, short ridges, and spurs as well as the delta (Thomson & Tangen, 2013). The Deposition of Fingerprint Fingerprints are formed when the friction ridge of the skin makes contact with the surface. The skin is comprised of pores that secret various substances both organic and inorganic (Girod et al, 2012). There are three glands that make it possible to secret materials from the skin this includes eccrine and apocrine glands, and sebaceous glands (Girod et al, 2012). The glands exude materials through pores into the friction ridges. However, when an individual touches other parts of the body such as armpits and forehead, consciously or unconsciously, the substances are transferred from the parts to the friction ridges, being that they are distributed all over the body (Thomson & Tangen, 2013). The eccrine glands secret water and trace amounts of other substances. The other substances include amino acids, proteins, fatty acids and sterol compounds as well as miscellaneous substances such as drugs (Girod et al, 2012). Apocrine glands on the other hand secret a thicker milky fluid and are more concentrated in the pubic area and the arm pits (Girod et al, 2012). They empty their secretions into the hair follicle then mixing with the sebaceous glands secretions. Most of the substances secreted here include proteins, carbohydrates, cholesterol, sulfates and iron. Another important gland is the sebaceous gland whose core secretion is sebum that mostly comprises of fatty acids and esters. The sebum is very important in lubricating the skin and reducing the evaporation of eccrine sweat (Girod et al, 2012). The secretions are meant to cool the body through sweat, excrete waste metabolic materials from the body and increase the surface area for friction on the ridges (Girod et al, 2012). They are discharged through pores that are well distributed on the friction ridges. Whenever there is contact between a friction ridge and a surface; either porous or non-porous, there is transfer of the secretions in the sweat produced from the pores on the ridges to the surface (Girod et al, 2012). This usually follows the pattern of the ridges on the skin of the finger. The Development of Latent Fingerprint Using Powders There is an array of methods that can be used in the development and thus enhancement of latent fingerprints (Thomson & Tangen, 2013). However, the powder method still actively remains the entrenched method for primary fingerprinting despite the associated factors that influence its use (Bandey, 2007). There are many types of powders and thus number or types of brush that are used with the powders to enhance the latent fingerprints collected or identified at different surfaces in the crime scene. The use of powders in the visualization of latent prints can be traced back to the 19th century (Bandey, 2007). Currently, the method is very dominant with the scene of crime officers, who usually collect prints from various crime scenes (Fieldhouse, 2011). The most invaluable tool that is used by forensic investigators is the powder method. It involves the use or application of finely divided powder formulations that adhere physically to the water and oily components of the latent prints. The powders can only be used in non-porous surfaces like glass, door knobs and table tops. The powders as aforementioned have affinity for moisture and oil and thus clings to the residue deposited on a surface by the friction ridge of the skin (Bandey, 2007). There is adhesion between the powders and the oily parts of the print. The aspects of the powder that determine the efficiency of visualization include the size, shape, surface area, and the components of the fingerprint residue (Bandey, 2007). The latter determines the choice of brushes that will be used. Most commercial powders consist of pigment and binders to provide adhesion without destruction of detail (Fieldhouse, 2011; Sears et al, 2012). As is with other evidences prior and after collection, the fingerprints are photographed prior to development and collection, in order to determine the choice of the method to be used and keep records respectively (Sears et al, 2012). The most effective and versatile powder is the carbon black that is mixed with effective carriers. It causes little or no substrate painting (Sodhi, 2001). Its mixtures produce a dark gray image that can be visualized on various contrasting surfaces. The powder has a unique characteristic of showing up on black glossy surfaces, through appearing in light color. The powder can be tagged with fluorescent dye stains so as to improve the visualization through photochemical procedures. The powder being so soft and fine is applied using soft brushes should be used (Sears et al, 2012; Sodhi, 2001). The most effective brush in this case is the animal hair brush (Sears et al, 2012). The most commonly used animal hair brush is that of the shape of the artist brush and is made from either squirrel or camel hair (Sears et al, 2012). Aluminium powder is also used in fingerprinting and is the most widespread (Sodhi, 2001). The efficiency of this powder type arises from its high sensitivity due to the flakes in it. The flakes range from 1-50 um in diameter and thus increase the surface area for adhesion to the fingerprint residues (Bandey, 2007; Sodhi, 2001). This is the best powder for all glass surfaces unless contamination limits its use. The flakes are very small; therefore, the most recommended brush to use is the glass fibre brush (Sears et al, 2012; Sodhi, 2001). However, on surfaces where glass fibre may be tangled or clogged up, for example contaminated surfaces, the zephyr style squirrel brush or the tapered polyester brushes are recommended (Sears et al, 2012). Black magnetic powder forms another important powder in fingerprinting (Sears et al, 2012). It is effective on PVC surfaces and textured surfaces such as paper (Sears et al, 2012). It has variations in color making it be selected based on the background of where the print is to be developed. This powder is applied by the magna brush that lacks bristles and is much softer causing less damage as well as no scatter of the flakes (Sears et al, 2012). The magnetic particles adhere to the substrate in the residue resisting removal (Sears et al, 2012). After rubbing over the appropriate powder, the fingerprints are photographed and then lifted using and adhesive tape (Sears et al, 2012). The tape is placed over the fingerprint and a roller used to flatten it to the surface (Bandey, 2007). The tape is then lifted and packaged on a contrasting tile for analysis in the lab (Sears et al, 2012). The chain of custody of the fingerprint collected must ensue to determine its reliability and thus admissibility in court (Bandey, 2007). Factors Influencing Latent Print Development There are different circumstances when latent fingerprints can be produced on objects at or in a crime scene. This means that there are factors that control the formation of latent fingerprints for forensic examinations (Thomson & Tangen, 2013). It is on the basis of the factors that a suitable method is chosen to visualize the latent fingerprint that is not macroscopically visible (Center for Applied Science and Technology, 2012). Age or Time since Deposition Research indicates that there is a direct relationship between time and degradation of latent fingerprints (Grey, 2013). As the age of the print increases, that is the time since deposition elongates, water evaporates from the print. This greatly depends on the relative humidity and ambient temperature (Deans, 2006; Grey, 2013). The powders are therefore rendered useless in such situations since they will have no substances to adhere to considering that most are aqueous dependent (Center for Applied Science and Technology, 2012). However, other methods such as ninhydrin and cyanoacrylate fuming can be used to visualize the prints (Center for Applied Science and Technology, 2012). As time precedes the target components of the latent fingerprints are lost and so does the contrast and quality of the latent fingerprint. However, the drying rate of latent print components is independent of relative humidity as the sweat residue has low water content (Grey, 2013). Nature of the Surface There are two major classifications of surfaces in fingerprinting; this includes porous and non-porous surfaces. The two govern the reproducibility of fingerprints on the surfaces as well as the choice of appropriate development techniques. Porous surfaces affect the amount of residue materials left by the friction ridges; only a fraction of the residues will be available during development (Fieldhouse, 2011). This is because much of the residue is absorbed and thus retained in the pores of the surface especially as time elapses (Fieldhouse, 2011). Examples of porous surfaces include cellulose based materials such as wood and paper. They absorb the materials at the surface leaving the large materials that cannot sip through the pores (Center for Applied Science and Technology, 2012). Some methods might be used in these surfaces. However, the only challenge is that partial prints will be realized which analyzing and comparison with the control samples may be hectic. Non- porous surfaces are the best for latent fingerprints since they do not absorb moisture that forms the largest percentage of the fingerprint residue (Fieldhouse, 2011). Most of the powders and chemicals used in fingerprinting require or depend on the aqueous component of the residue. Environmental Factors This mainly falls under the post deposition factors, since most of its effects are realized after deposition of the print (Center for Applied Science and Technology, 2012). They include conditions such as relative humidity and temperature. Optimal or ambient temperatures have been shown by studies to favor the development of fingerprints (Fieldhouse, 2011). Friction ridges can withstand mild temperatures of up to 200 0C beyond which most of its organic compounds are affected (Deans, 2006; Dominic et al, 2011). This means that fingerprints exposed to mild temperature ranges can still be recovered (Deans, 2006). The inorganic salts remain intact and unaltered especially chloride salts that are resistant of the heat (Dominic et al, 2011). Transport Factors This includes the manner of contact, contaminants on the hands, texture of the surface, and the amount of force or pressure (Fieldhouse, 2011). The larger the force or pressure exerted on the surface the more sufficient detail is deposited on the surface (Richmond, 2004). The presence of contaminants makes it easier to form fingerprints; however, some of these contaminants might affect the adhesion of the powder and fluorescent materials on the fingerprints thus hindering their development (Fieldhouse, 2011; Richmond, 2004). When there is loose contact between the fingers or friction ridge and the surface only partial latent fingerprints will be recovered compared to when there is complete contact (Richmond, 2004). Rational of the Present Study Most surfaces found on crime scenes are usually non-porous such as glass. Only on small occasions can a fingerprint be formed on porous materials. These surfaces include door knobs, cupboard handles, window panes and glasses on doors. Glass still forms the most common entry and exit points for most burglary criminals, despite being the most chosen form of architecture of most modern buildings, making it one of the most reliable points to collect latent prints (Sears et al, 2012). Most literature and studies have acknowledged the use of powders in glass surfaces and other non-porous surfaces to be the most effective. The best powders used in visualizing latent fingerprints prior to lifting are aluminium and granular black powder (Sears et al, 2012). The same way there are different powders is the same way there are different types of brushes that are used to apply the powders. The powders are dependent on the type of powder chosen and are ubiquitous due to the rising number of companies dealing in crime scene equipment and substances. This study aims to look into the different types of brushes that are used with aluminium and granular black powder, which are the most used powders in crime scenes. The study will look at the factors that affect the choice of a given type of brush as well as reveal the reasons as to why certain brushes are not being commonly used in dusting for fingerprints prior to collection. The aluminium powder is very sensitive and therefore must be applied using a brush that does not allow much of it to go to waste. This goes hand in hand with the safety of the workers. The choice of a brush is not only important to the method itself but also the environment and the worker applying the powder. There are different types of brushes depending on the powder being applied. Zephyr brush which is made of glass fiber is appropriate for applying aluminium powder. Marabou brush is used to blow off excess powder of any form reducing its spread in air. The feather duster brush is also used with the fluorescent powders that require build up of the powders. The study will reveal the importance of making good choices of brushes when applying different powders to develop or enhance latent prints. Additionally, the effectiveness of every brush will be demonstrated based on the economy and cost effectiveness that comes along with its use. The study shall therefore recommend the best brush to use with different powders. Bibliography Bandey, H.L 2007, Fingerprint Powders Guidelines, Home Development Scientific development Branch, 09(07), 1-5. Beresford, A.L., Brown, M. R., Hillman, A.R. & Bond, W.J 2012, Comparative Study of Electronic Enhancement of Latent Fingerprints with Existing Development Techniques, Journal of Forensic Sciences, 57(1), 93-104. Centre for Applied Science and Technology 2012, Fingerprint Source Book. Home Office. Available at:https://www.gov.uk/government/publications/fingerprint-source-book (Accessed: 1st December 2013) Deans, J 2006, 'Recovery of Fingerprints from Fire Scenes and Associated Evidence', Science & Justice, 46(3), pp. 153-168. Dominick, A.J., Nic Daéid, N. and Bleay, S.M 2011, 'The recoverability of fingerprints on nonporous surfaces exposed to elevated temperatures', Journal of Forensic Identification, 61(5), pp. 520-536. Fieldhouse, S 2011, Consistency and reproducibility in finger mark deposition, Forensic Science International, 207(1–3), pp. 96-100. Girod, A., Ramotowski, R. and Weyermann, C 2012, Composition of finger mark residue: A qualitative and quantitative review, Forensic Science International, 223(1–3), pp. 10-24. Grey, T 2013, Impact of Time, Weathering and Surface Type on Fingerprinting’, 2012, NCUR. Lambourne, G.T.C. 1977, A Brief History of Fingerprints, Journal of the Forensic Science Society, 17(2– 3), pp. 95-98. Richmond, S. 2004. Do fingerprint ridges and characteristics within ridges change with pressure? Australian Federal Police Forensic Services. Sears, V.G., Bleay, S.M., Bandey, H.L. & Bowman, V.J 2012, A methodology for finger mark research, Science & Justice, 52(3), pp. 145-160. Sodhi, G.S and Kaur, J 2001, Powder method for detecting latent fingerprints: A review, Forensic Science International, 120(3), pp. 172-176. Thompson, M.B & Tangen, M.J 2013, Human Matching Performance of Genuine Crime Scene Latent Fingerprints, American Psychological Association: Law and Human Behavior, 147-7307. Read More