Forensic Science Technician Skills - Term Paper Example

Forensic Skills Lab Report Name: Edith Cowan University 1. Introduction A finger print pattern or impression is a means of personal identification made by friction ridges of a finger. Finger printing is a vital method of forensic science applied in the recovery of fingerprints from a scene of crime (Lee, Palmbach, & Miller, 2001). Finger print impressions can easily be deposited on the surfaces of objects such as metals, glass or polished stone by epidermal ridges on human finger due to sweat from accrine glands. History of fingerprints The science of fingerprint and handprint can be dated back to thousands of years ago. It was used by early people to sign their work as they believed it was a very unique method to identify the works with themselves. Sir William Herschel (1833-1917) is known to be the first European to recognize how valuable fingerprinting is in personal identification. Evidence reveal that finger prints were a common means of sealing an agreement or a contract in India, where Herschel worked as a British administrator, and also in China hundreds of years ago (Gaensslen, 2001). A Scottish physician – Dr. Henry Faulds (1843-1930) was involved in the study of fingerprints. He found out that finger ridge details were unique, and that fingerprints could be used to trace criminals involved in a crime scene. Development in this field continued with the likes of Sir Francis Galton (1822-1911) and Juan Vucetich (1855-1925) contributing immensely (Gaensslen). Later on, Sir Edward Henry (1850-1931) devised a fingerprint classification method that is widely all over the world today (Gaensslen, 2001). Principle Human fingerprints are very unique, detailed, durable and difficult to alter. This makes them suitable for use as long-term markers of personal identity (Champod, Lennard, Margot, & Stoilovic, 2004). The palm, fingers and sole areas of human body have friction ridges that enhance grip and touch. These friction ridges are characterized by parallel flow lines with formations called whorls, deltas, arches and loops. These ridges are not even and unbroken as they run across the skin, but rather display several identifying features called minutiae (Mozayani and Noziglia, 2011). This makes a fingerprint and pores to be very unique. Fingerprint impressions are formed and transferred by use of ink, or any other suitable substance from the friction ridges onto a smooth surface like a fingerprint card. They are applied in concealing the identity of an individual, identifying individuals who are deceased, incapacitated or unable to identify who they are, for example in the aftermath of a disaster. Fingerprint analysis has been used since early 20th century to solve crimes (Lee, Palmbach and Miller). According to Leo (2015), the most recent discovery in this field was in 2015, when it was demonstrated that fingerprint tests can be used to identify an individual’s sex. Fingerprint Classification The most commonly used method of fingerprint classification is a modification of the method developed by Sir Edward Henry. In the Henry Classification System, each finger is assigned a number according to the order in which it appears on the hand, starting from the right thumb assigned number 1 and ending with the left little finger as number 10 (see figure 1). Fingers that have a whorl pattern are also assigned a numerical value (Diane Publishing Company, 1993). Finger numbers 1 & 2 are each assigned a value of 16, a value of 8 for fingers 3 & 4, fingers 5 & 6 assigned a value of 4, a value of 2 for fingers 7 & 8, and finally, a value of 1 for the final fingers 9 & 10. Fingers that lack a whorl pattern, but have a loop or an arch, are assigned a value of zero. The sum of even-finger values is then determined and taken as a numerator of a fraction, while the sum of odd-finger values is taken as the numerator. An additional value of 1 is then added to each sum obtained for the whorls with the maximum obtainable figure being 32 on each side of the fraction. Thus, in this classification, a fraction range from 1/1 to 32/32 is used. Having 1/1 would mean that there are no whorl patterns, while 32/32 would mean that there was a whorl pattern on all fingers (Hawthorne, 2008). Figure 1: Summary of modified Sir Edward Henry classification system 2. Aims of the fingerprinting laboratory The aim of this laboratory exercise was to: i. Identify characteristics of fingerprints; ii. Identify minutiae within a fingerprint; iii. Performing a comparison between unknown and known/reference fingerprints; and iv. Understanding the limitations of fingerprint technology 3. Methods Materials Used: i. White paper ii. Ink pads iii. Reference pictures of loops, whorls and arches iv. Magnifying glass v. Fingerprinting powder vi. Scotch tape (clear large packing tape) Procedure: Part 1: Inked Fingerprints Students were divided into groups of two and each student in the group made a set of their own finger prints from all the five fingers of one hand. This was done using ink pads and placing the fingerprints on a blank piece of white paper provided. The fingerprints were labeled as below: T – for thumb I – for index finger M – for middle finger R – for ring figure L – for little finger The fingers were then observed using a hand lens to try and identify the type of pattern on the fingers i.e. whorls, loops, or arches. The images obtained on the paper were then categorized based on the type of characteristic patterns observed. As many minutiae as possible were identified and listed. Part 2: Latent fingerprints The students placed their fingerprints on different objects in the laboratory room, lab tables, and pieces of glass and lab tables. The prints on these objects were then covered using fingerprint powder and brush. A large piece of scorch tape was then placed on the surfaces of the objects, then carefully peeled off the fingerprint and placed on a white paper. Identification of the whorls, archs and loops was then done within the lifted latent fingerprints. 4. Results and Discussion Part 1 The figures below show the fingerprint impressions obtained on the white paper from the left hand. The labels on the fingers start from the thump (T) to the little finger (L). Figure 2: Fingerprint impressions on white paper Fingerprint pattern analysis As noted in the background information, there are three main structures of interest in a fingerprint; whorls, loops and arches. Below are the images of magnified fingerprints taken from the fingers of the left hand placed on a glass surface. The fingerprints are labeled as demonstrated in the part 1 of the procedure – starting from the thump to the little finger. Figure 3(a): Finger #1 Left Thump: It is observed that the thump is comprised of several ridges entering from one side of the thump, forming curves, then leaving through the same side as they entered. This ridges clearly form loops with a delta (T-junction) and a core at the center of the pattern. The slope of the loop is towards the little finger. According to Henry classification, this loop is of a radial type. The types of minutiae that can be noticed on the fingerprint include ridge ending, bifurcations and enclosure. Figure 3(b) Finger #2 LI: This fingerprint portrays ridge lines gently rising to the center and forming a wave-like pattern. The ridges move in such a way that they enter through one side, form a rising arch at the center, and then exit by the other side. The ridges form an arch that can be classified as a tented arch. The types of minutiae that can be noticed on the fingerprint include ridge ending and bifurcations. Figure 3(c) Finger #3 LM: This fingerprint is characterised by a circular pattern forming whorls. Two deltas can be observed on both sides of the finger, with a central core. The structure of the whorls resemble a loop. Because of this, it can be categorized as central pocket loop whorls under Henry’s classification. Several bifurcations can be observed on the fingerprint. Figure 3 (d) finger #4 LR: From this fingerprint, circular patterns can be observed around the finger, forming circles within circles near the core. We can see two deltas and a core at the center of the pattern. Thus, we can classify this fingerprint as a whorl. Given that the flow of the loops resemble a loop with a whorl in the middle, the whorl can be categorized as central pocket loop whorls. The types of minutiae that can be observed on this fingerprint include ridge ending, enclosure and bifurcations. Figure 3(d) finger #5 LL: This fingerprint shows ridges that curve from one side of the finger to the other side, with a core at the center of the pattern, and a delta can also be seen on the lower side. Thus, an appropriate classification of the fingerprint is radial loops. The types of minutiae that can be observed on this fingerprint include ridge ending, ridge Island and bifurcations. Figure 4: The fingerprint card showing all the 10 fingers from both hands. We are interested in the left hand. Starting with #1 L. Thump, classified as a loop pattern under Henry pattern classification, #2 L. Index indicates a tented arch, #3 L. Middle showing whorl pattern, #4 L. Ring with a whorl pattern, and #5 L. Little indicating a loop pattern. The three fingerprint patterns are used to classify fingers in the Henry classification method. These are loops, arches and whorls. Minutia on finger patterns provide more unique details that can be used to do a closer comparison during a search for a match. These unique features are brought about by variances in the location of minutia (Hawthorne, 2008). Other variances may occur during the process of recording due to varying pressure and inking, and allowances need to be made for these variances. Part 2: Latent Fingerprints Below are the known/reference fingerprints collected from students. The fingerprints are marked as 1, 2, 3, 4, and 5 with a description of the pattern observed. Figure 5 (a) Reference finger #1: This fingerprint impression is comprised of ridges that enter from one side to form curves, and then exit via the same direction the ridges entered. There is a core at the center of the curving loop pattern and a delta on one side. This indicates that fingerprint forms a loop pattern. Figure 5(b) Reference finger #2: Like in figure 4(a) above, this fingerprint is comprised of ridges that enter from one side of the finger, form loops and then leave via the same direction they entered. The loop pattern has a core at the middle and also, a delta can also be noticed. Therefore, this finger has a loop pattern. Figure 5(c) Reference finger #3: This fingerprint also shows another looping patter. Loops are seen to emerge from one direction, curving to form loops. At the center of the loops is a core. A delta formation can also be observed. Figure 5(d) Reference finger #4: Unlike the first three fingers analyzed above, this one has got a circular pattern with two deltas. This circular patterns resemble central pocket loop whorls. Figure 5(e) Reference finger #4: Circular patterns can be observed from the above fingerprint, with a delta to form a looping fingerprint pattern. These circular patterns form loops that emerge from one point and exit from the same direction they come from. A close comparison of ridge pattern or loops in this fingerprint shows resemblance with those in the unknown fingerprint in figure 5. Figure 6: Unknown fingerprint: This fingerprint is compared with the reference fingers in figure 4(a – e) above. This fingerprint has circular patterns that curve to form loops. A close observation of this fingerprint resembles the one in figure 4(e) because they share all the features and have a similar finger pattern. Latent fingerprinting is an invisible print that is formed when one touches a surface. Visualization of latent fingerprints can be done through chemical, electronic or physical techniques. They display lesser details compared to the actual ridge patterns as shown in the figures of reference/known fingerprints and the latent fingerprint in figure 5. Fingerprints are characterized by friction ridges that form certain patterns allowing for examination and classification. Finger ridges are not even, but rather display some variations within the ridge patterns (Leo, 2015). These several variations or discontinuities of ridges (referred to as minutiae) are as a result of pressures and external growth. The type and specific location of minutiae are unique and form the basis for fingerprint comparison. These variations form the basis of detailed distinction of fingerprints. In a nut shell, the basic principles of application of fingerprinting technology in forensic science are based on the fact that fingerprints cannot be changed over a person’s lifetime; the finger ridges possess different ridge characteristics; and that the ridge characteristics provide efficient means of examination and classification (Champod, Lennard, Margot, & Stoilovic, 2004). Limitations of fingerprint technology Based on the activities undertaken in this lab, it is noted that fingerprinting has some limitations. Some of the limitations of this technology include: i. There is a possibility that a given fingerprint could have more than one interpretation. Also, the impression made by a finger may vary as a result of variance in inking and pressure. ii. Another limitation of fingerprint technology is the fact that there must be a known fingerprint for comparing with the collected fingerprint. iii. It is difficult to tell the time when a fingerprint was left on a surface, or the circumstance under which the fingerprint was deposited. iv. A fingerprint does not tell about the race or age from a latent print. Recent advances have shown that it is possible to reveal a party’s sex if sufficient DNA is collected. v. Fingerprints can be damaged or distorted to a point where identification may be difficult. Conclusions In this lab, we were able to identify characteristics of fingerprints and the types of minutiae from finger impressions collected from a left hand. Comparison of latent fingerprint and known/reference fingerprint was also successfully performed to identify an unknown print. The fingerprints were classified based on three main categories of Henry classification, which are loops, arches and whorl. By observation and comparison of ridge features on the reference fingers, we were able to identify the unknown fingerprint. The analysis of fingerprints for identification and matching purposes requires that a comparison of several features of the fingerprint is performed. These features include characteristics of ridges to determine the pattern, and types of minutia, which are unique features embedded in the ridge patterns. Finger printing identification is of great importance in criminal investigation due to their uniqueness and persistence. Even though this technology has been in use since the 20th century, it has some limitations. References Read More