PAPER No. 3: Fingerprints & Other Impressions MODULE No. 32: Footprints and their Importance

Transcription

1 SUBJECT Paper No. and Title Module No. and Title Module Tag MODULE No.32: Footprints and their Importance FSC_P3_M32

2 TABLE OF CONTENTS 1. Learning Outcomes 2. Introduction : Footprints 3. Purpose of Investigation of Footprints 4. Types of Footprints 5. Collection of Footprints 6. Analysis of Footprint 7. Evidence Submission and Examination 8. Shoe Print 9. Summary

3 1. Learning Outcomes After studying this module, you shall be able to- Know about Footprint and their collection Learn about various types of Footprint Examination of Footprint and their evidence submission 2. Introduction: Footprints Examination and comparison of design, size or shape of footprint is useful in criminal investigation for leading a case in appropriate direction. Several research has been carried out to prove that the foot prints are unique to a person and have high value in court of law. In foot prints the parameters that are taken into consideration are the dimensions of the stride, footprint s location, its size and shape, the angulations, interspaces, deepness, the outer margins, creases in heels, information regarding the gait pattern from the injuries and accidental damages, length of legs and height of the individual range of body weight and interrelated movement of the foot, ankle, leg and the body that are individualistic to that particular person. 3. Purpose of Investigation of Footprint The purpose of the present investigation is to study the shape, size, alignment of toes, humps, creases, cuts, cracks, pits, etc., of the foot so as to draw conclusions for individualizing characteristics. In addition, the occurrence or frequency of some of the foot characteristics was also recorded in the population under study. Establishing a relationship between the accused and crime is of paramount importance in every crime scene investigation. There are 26 bones, 33 joints (20 of which are actively articulating) and more than 100 muscles, tendons and ligaments in each human foot along with considerable variations in its component parts. These variations are reflected in the degree of influence of every part to the function of the foot as a entire. These variations are responsible for differences in pressure distribution and weight bearing through gait, making each footprint unique.

4 4. Types of Footprint 1) Visible Print A visible print is a transfer of material from the shoe or tire to the surface. This kind can be observed through naked eye without extra aids. For instance, bloody shoe prints leftward on carpet or tracks left by muddy tires on a driveway. 2) Latent Print A latent print is not easily observable to the bare eye. This is formed by static charges between the sole or tread and the surface. Investigators uses powders, chemicals and alternate light sources to observe these prints. Illustrations comprise shoeprints identified on a tile or hardwood ground, window sill, or metal counter, or tire tracks detected on road surfaces, driveways or sidewalks. Others: 1) Phalange marks Phalange marks are created by the phalanges of the toes and are imprinted in form of toe stems. The presence, position, shape and size of the phalange mark from the characteristic feature of footprints and can help in personal identification. 2) Crease marks Crease marks are caused by skin folds of the plantar surface of the foot. Some of the folds are long lasting while others are not. Both types of creases form useful evidence to identify individuals. Their presence, position, size and shape are characteristic of a person. The existing study demonstrations that in various cases, there may be no crease mark or there are one or two or several creases, correspondingly in some individuals, creases are vertical horizontal or crossed, in others or they may be in different directions. Besides this in flatfooted subjects of the present study, the crease marks are frequently seen at the centre of the foot. It is further observed that the number of crease marks in a flatfoot is more than in normal foot.

5 3) Pits, corns, deformity and crack marks It is well known that the individuals who have the habit of walking barefooted, their plantar surface forms pits, corns, cracks, cuts, etc. They have their corresponding marks in the imprints. The damage in the form of pits or cracks is individualistic in nature and permits definite identification of the marks in the respect of its source, thus linking the mark with the foot of a person. In the North Indian Gujjars of the present study, clearly demonstrates the formation of pits that might be due to the habit of walking barefooted. An unusual flat ridge in the instep area of both left and right footprints is seen as an example of deformity. 4) Flatfoot character Flatfoot is a condition, in which complete instep region of the plantar surface of the foot is impressed on the surface. The flexed or curved area is not visible in flatfoot as in normal foot. That is, the medial and lateral borders of the foot can clearly be discernible in the flatfoot. This condition is considered as a deformity and the recruitment into the military and police forces is restricted for such persons having this condition. In the present study, the flatfoot condition exists in 1.54% of the population. The condition shows a significant bilateral variation in both left and right feet of some persons. It is found, in an individual, as shown in, one foot is flat and the other is normal. The frequency of the flatfoot condition is more on the left side (1.54%) than on the right side (1.05%). The feature may be helpful in approaching personal identity in the exclusion and inclusion of certain suspects. 5. Collection of Footprint Footprints can be considered as a type of evidence and collection can be done from various crime scenes. The stride dimension, location of each footprint, its shape, size, angulations and deepness, interspaces and outer margins, heel creases, injuries or accidental damages provide indirect information with regard to gait pattern, height of the person, length of legs, range of body weight and interrelated movement of the foot, ankle, leg and the body that are individualistic to that particular person. Thus, the footprints whether complete or partial or even a small portion can provide evidence, which may indicate the skeletal and body structure of the person who made it.

6 In a foot, the specific arrangement of the bones in respect of to each other and the manner they are kept by connective tissues are the result of heredity and environment and differ not only from individual to individual but also from left to right feet of the same individual; even identical twins do not make identical footprints. For impressions in soil, snow or other soft surfaces, casting is the most commonly used collection method. For imprints, examiners generally try to collect the entire object containing the imprint, such as a whole sheet of paper or cardboard with a shoe print. When that is not possible, for instance, if the print is on a bank counter, the examiner would use a lifting technique to transfer the imprint to a medium that can be sent to the laboratory. As with any evidence found at a crime scene, shoeprints and tire tracks must be properly documented, collected and preserved in order to maintain the integrity of the evidence. Impression evidence is easily damaged, so steps must be taken to avoid damage to the evidence. This includes securing and documenting the scene prior to collecting any evidence. In the case of impression evidence, general photographs of the evidence location in relation to the rest of the scene are taken, along with high-resolution images of the individual imprints or impressions. Examiners may use alternate light sources or chemical enhancers to capture as much detail as possible, especially with latent imprints. Properly photographing impressions is crucial. Since there is only a slight difference between different shoe sizes, if the photographs are not taken at a 90 angle to the impression, then the true size cannot be produced in order to compare to the actual shoe. Whenever possible, impression evidence is collected as is and submitted to the laboratory for examination. For shoeprints and tire tracks that cannot be picked up, various lifting techniques are used to recover the evidence. These include: Adhesive lifter A heavy coating of adhesive lifts the imprint from smooth, non-delicate surfaces such as tile or hardwood floors, metal counters, etc. It is usually used in conjunction with fingerprint powders.

7 Gelatin lifter A sheet of rubber with a low-adhesive gelatin layer on one side that can lift prints from almost any surface, including porous, rough, curved and textured surfaces. It is less tacky and more flexible than an adhesive lifter, allowing it to pick up a dusty shoeprint on a cardboard box, for example, but not tear the surface of the box. Electrostatic dust-print lifting device- A tool that electrostatically charges particles within dust or light soil, which are then attracted and bonded to a lifting film. This method is best for collecting dry or dusty residue impressions on almost any surface, even the skin of a cadaver. Any plastic, or three-dimensional, footwear or tire impressions can be collected by casting. Casting uses a powdered stone material, such as dental stone, that can be mixed with water and poured into the impression. When it dries, this method creates a three-dimensional model of the impression. Imprints and impressions may be further processed to enhance or bring out additional minute details. For example, a digital enhancement program such as Adobe Photoshop can be used to improve the quality of a photographed tire track. Fingerprint powders and chemical stains or dyes can enhance image colour or increase the contrast against the background. This enables lifted or casted evidence to be photographed or scanned. Comparison samples are usually taken from suspects or suspect vehicles. Shoe samples should be packaged to avoid cross-contamination and tire samples should remain on the vehicle. The Scientific Working Group on Shoeprint and Tire Tread Evidence (SWGTREAD) has a published standard that discusses the minimum qualifications and training for footwear/tire track examiners. Additionally, the International Association for Identification (IAI) offers a recommended course of study for footwear and tire track examiners that takes participants through more than 550 hours of training. The IAI also certifies footwear (but not tire track) examiners.

8 6. Analysis of Footprint Detection, documentation, photography, and collection of imprints and impressions occur in relation to crime scenes of many types. Analysis of impression evidence is typically performed at a public crime laboratory or private laboratory by experienced examiners. Tools and Techniques During the examination and comparison, examiners use tools such as dividers, callipers, special lighting and low magnification. Examiners measure the various elements within the tread design as well as the length and width of the impressions, and then compare those measurements to what is seen in the crime scene print or impressions. Low magnification and special lighting are sometimes used to determine if various characteristics are accidental or something that was created during the manufacturing process. Examiners perform side-by-side comparisons by placing the known shoe or tire alongside the crime scene print so that corresponding areas can be examined. Test prints are also compared to the crime scene print. Digital images on double or triple computer monitors can also be used during the comparison. Footprint analysis The footprint of an individual is as unique as his fingerprints and as such can be used for fixation of the identity. Even monozygotic twins can be identified based on footprints. The footprints that are produced while standing are smaller as compared to those produced while walking. When a suspect is arrested, his barefoot impressions can be compared to the bare or socked impressions at the crime scene, or to impressions left inside footwear that have been recovered. In the foot examination, the shape, outline and position of parts of foot are studied. Comparative studies have shown that there are wide variations among different persons and significant similarities for multiple impressions taken from the same person.

9 Footprints can give valuable information regarding any pathology or individual characteristics and this will aid in the identification process. Three methods for barefoot examination are commonly employed I. Gunn Method: Here well recognized identification points of foot are connected with one another by using a series of measured lines. II. Optical Centre Method: A distinct point on the foot is identified and concentric circles are drawn in its most suitable location. This point is then isolated and then connected to other recognized regions of the footprint by means of lines. III. Overlay Method Here outline of an identified footprint is drawn and positioned over an unknown footprint and compared. Features such as crease lines, shapes and positions of toes etc. are matched. 7. Evidence Submission and Examination Preferably, the suspect s shoes and/or tires are surrender to to the lab with the seized evidence. Examiners will use the submitted shoes and/or tires to make test standards, impressions of a known source, which can then be compared to the collected evidence. This is usually done using transparency overlays or side-by-side comparisons. For example, in a case from Florida, a bloody shoe print was found on the carpet in the home of a murder victim. The print indicated that there was a hole in the shoe that left the print. Investigators collected and forms test prints of the shoes from persons said to be at the scene at the time of the crime. The identification of culprit by overlapping the blood-spattered shoeprint from the crime scene with test print by footwear examiner made from the accused s shoe. In certain cases, an investigator should be requested to give shoes or tires of other persons for elimination purposes, like as from a cohabitant of a home or from a first responder to a crime scene.

10 8. Shoeprint Analysis Two types of markings are present on the shoes-primary and secondary. The primary markings give the information about the maker of shoe or it s sole while the secondary markings are due to wear and tear of the sole associated with use. If there is an incidental finding it will be useful because of its uniqueness and it is desirable to find its corresponding shoe before that feature gets lost with time or damage. The information from shoes can be obtained in three different ways- (a) (b) (c) Outer impressions, Inner impressions and Other evidence from shoes. (a) (b) (c) Outer impressions: They are the imprints left on an entity that was produced by interaction with footwear. They can be found on the floor, doormats, carpet, doors or even the body of victim (e.g.: due to kicking). Inner impressions/imprints: They are imprints left in the inside of shoe by contact from the person s foot. Analysis of the insole impressions can be used to link a person(s) to a piece of footwear. Other evidence: It is in the form of body hair, body fluids, skin tags, dust particles, glass fragments that may be found on the shoes. The study of this trace evidence could be used to link the footwear to a location or owner. DNA can be one of the contributing factors in forensic evidence from shoes.

11 9. Summary 1. The purpose of the present investigation is to study the shape, size, alignment of toes, humps, creases, cuts, cracks, pits, etc., of the foot so as to draw conclusions for individualizing characteristics. 2. Phalange marks are created by the phalanges of the toes and are imprinted in form of toe stems. 3. Flatfoot is a condition, in which complete instep region of the plantar surface of the foot is impressed on the surface. 4. The footprint of an individual is as unique as his fingerprints and as such can be used for fixation of the identity. Even monozygotic twins can be identified based on footprints. 5. Two types of markings are present on the shoes-primary and secondary. The primary markings give the information about the maker of shoe or it s sole while the secondary markings are due to wear and tear of the sole associated with use.