2.1. Fingerprints and handprint patterns have been used as a means of personal identification for thousands of years. Records indicate the use of fingerprints and handprints as marks of authenticity in China at least 2000 years ago. The first scientific recognition of fingerprints in the West came from writings in the late seventeenth century. In 1684, an English plant scientist Dr Nehemiah Grew studied and described the ridges, furrows and pores of human hands and feet, and in 1686 an Italian professor Marcello Malpighi, using the newly invented microscope, referred to the varying ridges and patterns of human fingerprints, stating that the ridge detail was drawn out into loops and whorls, descriptors still used today. Professor Johannes Purkinje, a professor of anatomy at the University of what was then Breslau, in 1823 described and illustrated nine fingerprint pattern types in considerable detail, naming each pattern type and devising rules for their individual classification.
2.2. The first recorded systematic capture of hand and finger images uniformly taken for identification purposes was implemented in 1858 by Sir William Hershel, who, while working for the Civil Service of India, used prints to distinguish between employees. He accumulated a sizable fingerprint collection, which he offered as empirical proof to what had frequently been asserted in theory: that each fingerprint was unique and also permanent to the individual.
2.3. A Scot was responsible for a major milestone in fingerprint history and the use of inked impressions. In 1880, Dr Henry Faulds, while working as a medical missionary in Tokyo, was also conducting research into fingerprints. He proposed that because the ridge detail of any one fingerprint is unique they could be classified and used to solve crimes. He suggested that fingerprints could be used in an investigation to eliminate an accused individual and also to prove identity, by comparison of finger marks left at scenes of crimes by the criminal. Like Sir William Herschel, Dr Faulds had discovered that oil and sweat from the pores resulted in latent (invisible) prints that could be developed with powders. His proposition moved fingerprint images beyond civil applications, such as contracts, and into the forensic arena.
2.4. Other means of identification were also being considered, one being anthropometry, the measurement of the human body. One system was developed by Frenchman Alphonse Bertillon and from 1878, numerous specific measurements of an arrestee would be taken, and other physical characteristics noted, including, from 1894, fingerprints. English scientist Sir Francis Galton, having considered this system, in 1892 published a book entitled 'Finger Prints' on the use of fingerprints for identification which created the basis for fingerprint classification. He categorised fingerprints into three pattern groups: arches, loops and whorls. Sir Edward Henry set about finding a formula that would allow a fingerprint collection of several thousand to be filed and retrieved, and published 'Classification and Uses of Fingerprints' in 1900. Dr Edmond Locard, later head of the forensic science laboratory in Lyon, and a pioneer of poroscopy, reviewed the various systems of personal identification in 1906 and was convinced of the superiority of fingerprinting (dactyloscopy). The classification method for fingerprints gradually replaced the anthropometrical records of 'bertillonage'. The Henry Classification System remained the standard until the introduction of automated systems.
2.5. Fingerprints and other 'friction skin' patterns are used as a means of identifying individuals, particularly in criminal justice systems worldwide. Professor Christophe Champod, Professor of Forensic Science at the University of Lausanne, gave a general explanation to the Inquiry about the premises on which fingerprint evidence is based and the nature of the work that is undertaken.2
Friction ridge patterns in skin
2.6. The surface of the skin on the tips of the fingers, palms of the hands and soles of the feet, unlike the skin on most of the rest of the human body, is continuously corrugated with narrow ridges. The purpose of the ridges is to increase the friction between these surfaces and the surfaces with which they come into contact, hence the terms 'friction ridges' and 'friction ridge analysis'.
2.7. The friction ridges form patterns. Sometimes narrow and often fragmented ridges appear between normal friction ridges. These are called incipient, immature, rudimentary, subsidiary or nascent ridges. Friction ridges vary in length from a section of ridge with one pore to a ridge with hundreds of pores.
2.8. The 'blueprint' for a digit's friction ridges is laid down in the skin's lower layer, the dermis, in the early stages of foetal development, and the friction ridges develop in their definitive form before birth. The cells in the upper layer, the epidermis, are constantly regenerating during life but because the pattern in the epidermis reflects the structure of the dermis beneath, it is only if the dermis itself is cut that a scar will remain visible on the skin's surface. Friction ridges persist throughout life save where there is permanent scarring. The persistence of friction ridge detail throughout life is the first basic premise of fingerprint identification.
2.9. The second is that the arrangement of the friction ridges varies from one fingerprint to another, both as between the fingers of any one individual and between donors. This 'between sources' variability3 of the arrangements of ridges in sequence is extreme to the point that no two individuals showing the same arrangements have ever been found. 'Uniqueness' applies not only to the detail of the complete fingerprint but also to small areas.4
2.10. It is the persistence and uniqueness of the pattern of the ridges in skin that in combination mean that fingerprints provide a means of discriminating between one individual and another. These premises are at the heart of the work variously described as fingerprint ridge analysis, fingerprint comparison, fingerprint identification or 'individualisation'. In some jurisdictions 'judicial notice' has been taken of permanence and uniqueness as matters of fact;5 'judicial notice' meaning that the reliability of these propositions is regarded as being so well established that any challenge to them in court would be regarded as manifestly unfounded.6 Nonetheless, some have claimed that the premises have not been scientifically proven. The National Academy of Sciences7 concluded that there is some scientific evidence in support but research to validate the concepts is ongoing.8
Three levels of detail
2.11. Overall friction ridge patterns vary within limits which allow for classification and the organisation of prints into groups. Two focal points are a delta, where three ridge systems meet, and the core, generally at the centre of a fingertip, where ridges 'recurve' with the most angle or slope. Practitioners used standard 'labels' to distinguish between various flow patterns they observe, such as loop to the right, loop to the left, whorl or arch. A loop has only one delta (either to the left in a right loop, or to the right in a left loop),9 a whorl generally has two deltas, and an arch has no delta.
2.12. Classification is a tool for the efficient search of available prints. The concept tended to be simplified to saying a print was a loop or a whorl or an arch but the reality of the flows on fingertips means that in fact there is a continuum of shapes, a progression between what might be classified as a whorl or an arch. Some patterns are more common than others, for example loop patterns are frequent and arches infrequent.
2.13. This general flow pattern or overall friction ridge pattern, the 'first level detail', guides a comparison towards like formations. Where a mark and a print differ in their level one detail (e.g. one is a whorl and the other an arch) the possibility of a match is excluded. Coincidence of level one detail is not itself sufficiently discriminating to 'individualise'.
2.14. 'Level two detail' refers to the specific formation, the detailed path of the individual friction ridges and how they deviate. 'Galton characteristics', 'points' and 'minutiae' are all terms for level two features. The two main types of level two detail are a ridge ending (where a ridge terminates), and a bifurcation (where it splits into two branches). These can be combined: for example a ridge might divide and after a short distance re-form as a single ridge, and the two bifurcations, taken together, would form a 'lake'; or there can be a short length of ridge, with a ridge ending at either end, which can be described as an 'island'. The detail can include features such as warts, scars, creases and wrinkles. Second level detail has 'individualising power'.10
2.15. 'Level 3 features' need higher magnification to be visualised easily and the focus is on the edges of the ridges and the pores and their shape.
Crime scene marks
2.16. Some fingerprint evidence at a crime scene or on a related item may be visible i.e. it can be seen without any particular treatment. Examples are where a mark is formed by a finger which has been contaminated with a coloured substance such as blood or where a finger removes material which is already on a surface such as dust.
2.17. More often fingerprint evidence is latent. A fingerprint is a complex mixture of natural secretions and contaminants from the environment, and there are a variety of techniques to make latent fingerprints visible.
2.18. Scenes of crime and objects relevant to a crime are examined by specialists to reveal any impressions that may be present, using various types of powder and chemicals suited to the kind of surface. Any impression found is preserved either by being lifted using tape or by being photographed and passed to a fingerprint examiner, a person who through training and experience is skilled in the identification of marks.
Plain and rolled prints
2.19. In 1997 the finger and palm prints of known persons were usually taken by police personnel on fingerprint 'ten-print forms'.11 Generally two impressions were taken from each digit, one 'rolled' (where the side of a finger was placed down and the finger rotated) and one 'plain' (where all the fingers were lightly pressed down on the form with a single touch). The fingerprint forms for Ms McKie and Mr Asbury had plain and rolled inked prints.
2.20. The digits are numbered from one to ten: the digits on the right hand run from 1 (thumb) to 5 (little finger) and those on the left hand from 6 (thumb) to 10 (little finger). So for example the gift tag mark, XF, which was identified as being Mr Asbury's right forefinger was his "No. 2",12 and Y7 which was identified as being Ms McKie's left thumb was her "No. 6."13
2.21. Fingerprints may be taken from the body of a deceased person, as happened with Miss Ross. The 'dead print' forms for Miss Ross had only one impression per digit.14
2.22. Plain and rolled prints taken of the same finger may show more or less of the finger's surface area.
The use of automated systems
2.23. Human sight is central to fingerprint work, and has not been displaced by technology. Automated Fingerprint Identification Systems (AFIS) were introduced towards the end of the twentieth century to assist with the growing volume of prints. AFIS use computer technology and specially coded digital images which can be searched and compared. AFIS processing makes it possible to search marks found at crime scenes against an entire collection of fingerprint files.
2.24. SCRO witnesses described the Automated Fingerprint Recognition system, AFR, that was at the time in use in Scotland. The computer could not use a mark which was distorted, twisted or superimposed.15 For marks selected for use, the basic searching criteria would be assessed i.e. the finger which the examiner considered had made the impression, the pattern type and a clear area of characteristics. This information would be put into the system and the computer would produce a list of candidate images, scored in order of probability.16 'IDENT1' replaced AFR in 2006. It is a single database of finger and palm prints for Scotland, England and Wales.17
2.25. Examiners take the pool of prints retrieved from the system and carry out their standard comparison work, comparing the crime scene mark with those prints.
2.26. Fingerprint comparison work can also be carried out 'manually' using the prints of known individuals not previously stored on the computer system. The prints will be provided by the police for individuals who may be of interest to the police or who require to be eliminated from the particular investigation.
Fingerprint comparison work
2.27. Fingerprint examiners carry out a visual comparison of a crime scene mark and prints from a known individual. A mark left on a surface is generally being compared with a print taken in controlled conditions18 for example using ink or, in current practice, 'Livescan', an optical device used to capture impressions digitally.
2.28. The comparison process is to determine whether a mark and a print match so that the mark can be 'individualised'. By the mark being 'individualised' fingerprint examiners mean that it can be attributed to the known individual to the highest level of specificity: it is unique to that one individual out of the whole human population throughout history.
2.29. The sources that the examiner uses in the comparison process, the mark and the print, are both impressions.
The premises of fingerprint identification
2.30. A number of commentators highlight that the two basic premises explained in paragraphs 8-10 relate to friction ridge patterns in skin, whereas fingerprint examiners work with impressions. "Statements about the two media are not necessarily interchangeable."19 Simon A. Cole, in an article entitled 'Is Fingerprint Identification Valid? Rhetorics of Reliability in Fingerprint Proponents' Discourse',20 argued that there is a distinction between two propositions:
The reliability of fingerprint evidence depends on both propositions but Cole argued that the second does not necessarily flow from the first.
2.31. The National Academy of Sciences makes a similar point:
"Some scientific evidence supports the presumption that friction ridge patterns are unique to each person and persist unchanged throughout a lifetime. Uniqueness and persistence are necessary conditions for friction ridge identification to be feasible, but those conditions do not imply that anyone can reliably discern whether or not two friction ridge impressions were made by the same person. Uniqueness does not guarantee that prints from two different people are always sufficiently different that they cannot be confused, or that two impressions made by the same finger will also be sufficiently similar to be discerned as coming from the same source. The impression left by a given finger will differ every time, because of inevitable variations in pressure, which change the degree of contact between each part of the ridge structure and the impression medium. None of these variabilities-of features across a population of fingers or of repeated impressions left by the same finger-has been characterized, quantified, or compared."21
2.32. The English Law Commission went one stage further by highlighting that fingerprint examiners can be required to work with partial impressions:
"Even identical twins have different fingerprints. It therefore seems that fingerprints are generated by a combination of genetic and environmental factors in the womb, meaning that it is extremely unlikely that two individuals will share a complete fingerprint. However, this does not mean that an individual will always be correctly identified from a crime-scene print, given the greater possibility that two individuals will share part of a print and, more importantly, the difficulty of discerning whether or not a partial or smudged crime-scene print matches a print taken from the accused in controlled circumstances."22
2.33. The second basic premise of fingerprint comparison work does extend to the proposition that the details in small areas of friction ridge patterns are unique and never repeated.23 As the Law Commission recognises, the pertinent question, which is how small an area can yield a pattern sufficiently unique for a reliable individualisation, cannot be divorced from the quality of the impressions being compared.24
2.34. This necessitates close attention to the nature of impressions.
The variability of impressions
2.35. The friction skin is a three-dimensional structure. On contact with a surface a two-dimensional impression may be left of the pattern of the skin. How well the details from three-dimensional ridges are reproduced in the two-dimensional impression (mark and print) is often referred to as the 'clarity' or 'quality' of the fingerprint. This varies depending for example on the nature of the surface and of the contact made.
2.36. Many of the minute details that make small areas of friction skin unique do not survive the transition from finger to impression. The pressure used when the impression is made, 'deposition pressure', generally changes the shape of the friction ridge by flattening or broadening each ridge. Friction skin is flexible, but within limits, and this can result in sideways sliding of ridges, showing in an impression as smearing and sometimes called 'pressure distortion'.25
2.37. Various 'substrates', the surfaces on which fingermarks are left, can cause distortion or interfere with the deposition of a print, affecting its appearance and clarity.26 The technique used to detect and develop an impression can also affect how it appears.27
2.38. Impressions from the same digit vary, even impressions taken in controlled conditions. Professor Champod described this as 'within source' variability.28
2.39. In his evidence to the Inquiry Professor Champod displayed a series of impressions made by the same finger.29
(i) The first series of three images corresponded to 'prints' taken under controlled circumstances and comprised (1) an inked impression "rolled nail-to-nail" with ink, (2) an impression taken using a high resolution Livescan (a 'flat' impression, not rolled, with the finger simply laid on the surface of the sensor) and (3) an impression taken using a lower resolution Livescan device.30 The three impressions were not identical. They were all different but showed features which an examiner could relate.
(ii) The second series, corresponding to 'marks', were contacts on (1) a sheet of plastic, (2) a sheet of paper and (3) adhesive tape.31 These too were different not only from the 'prints' but also from one another, with, for example, one mark showing more information of the friction ridge skin than another, and the substrate or development technique affecting the visibility of features.
The fingerprint examiner's task
2.40. The issue for the examiner in comparing a mark with a print is whether an individual can be distinguished based on the material left as the mark and the material available as the print.
2.41. The comparison the fingerprint examiner makes is of "degraded information"32 compared to the information which would be gathered ideally by looking at the finger itself. Both mark and print are merely impressions of finger ridge detail, each of which is a more or less partial reproduction of the friction ridge detail in the skin subject to a number of distortions due to the manner of deposition, the surface on which the deposition took place and the means of development and capture of the impression.
2.42. Whether or not fingerprints are in fact unique (i.e. whether the characteristics of a fingerprint, or more relevantly a small part of a fingerprint, may be shared by anyone else) is currently under debate33 but, as far as fingerprint comparison work is concerned, "[t]he real issue is more on the distinguishability than on the uniqueness. It is how good examiners are in their capacity to distinguish marks and prints when they come selectively from the same persons or from different persons."34
2.43. When carrying out a comparison, examiners require to be able to distinguish between (a) 'within source' variations and (b) 'between source' variations in order to ascertain whether a mark and print are from the same donor. The existence of a between source variation would exclude a match. Assuming that there is no between source variation, the examiners require to ascertain the similarities and to distinguish between those that may be common and those that are 'sufficiently' discriminating to individualise. The exercise depends in part on the quality of the impressions and the skill of the examiner: "distinguishability or variability of prints/marks depends crucially on the examination method but also on the intrinsic qualities of the prints/marks to display selective features (extensiveness, clarity, etc.)."35
Opinion not fact
2.44. The permanence (or persistence) and uniqueness of friction ridge detail in skin mean that fingerprints can provide a reliable basis for identifying an individual. Whether or not any particular individual can be reliably identified from a particular crime scene mark involves consideration of a number of compounding variables, including (1) the skill, training and aptitude of the particular fingerprint practitioner, (2) the quality of the crime scene mark and the print of the known individual and (3) the criteria applied in determining whether any particular combination of matching ridge characteristics is 'sufficient' for individualisation.
2.45. The decision whether or not a mark can be individualised is potentially a complex one calling for a series of subjective judgments on the part of the examiner. The decision is one of opinion, not fact.
2.46. Further detail on the variability of impressions is given in Chapter 19. The subjective questions that require to be considered by an examiner carrying out a comparison are discussed in Chapter 35 and the background to 'sufficiency' (at one time addressed in the UK by the '16-point standard' and now by the 'non-numeric' approach) is given in chapters 32 and 33.
1. For more information see for example Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis: An Introduction to Basic and Advanced Ridgeology. Boca Raton: CRC Press, 1999; Champod, C., Lennard, C., Margot, P and Stoilovic, M. Fingerprint and Other Ridge Skin Impressions. Boca Raton: CRC Press, 2004; Farelo, A. (2009) A History of Fingerprints. (Interpol) URL:
2. Professor Champod 25 November page 1ff and ED_0005. See also Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999
3. ED_0005 page 74
4. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999, pages 85 and 91-92
5. Champod, C., Lennard, C., Margot, P and Stoilovic, M. Fingerprint and Other Ridge Skin Impressions, 2004, page 15
6. The Law Commission Consultation Paper No. 190, The Admissibility of Expert Evidence in Criminal Proceedings in England & Wales, 2009, para. 6.54(1), URL:
7. Committee on Identifying the Needs of the Forensic Sciences Community, Committee on Science, Technology and Law Policy and Global Affairs, Committee on Applied and Theoretical Statistics Division on Engineering and Physical Sciences, National Research Council. Strengthening Forensic Science in the United States: A Path Forward, Washington, D.C.: National Academies Press, 2009, page 143
8. US Department of Justice, Office of the Inspector General (2011) A Review of the FBI's Progress in Responding to the Recommendations in the Office of the Inspector General Report on the Fingerprint Misidentification in the Brandon Mayfield Case, URL:
http://www.latent-prints.com/images/FBI%20Mayfield%20Progress%20062011.pdf, pdf page 7
9. The left and right references are to the direction the ridges flow out of the pattern.
10. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999, page 96
11. They now have 'Livescan'.
14. DB_0142h and DB_0017h
15. FI_0046 para 87 Inquiry Witness Statement of Mr Mackenzie
16. FI_0046 paras 76-82 Inquiry Witness Statement of Mr Mackenzie and FI_0055 para 22 Inquiry Witness Statement of Mr MacPherson
17. e.g. Mr Nelson 13 November pages 100-101
18. A mark to print search. Examiners also do print to print, mark to mark and print to mark searches - see e.g. glossary in SG_0375.
19. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999, page 93
20. Cole S.A. Is Fingerprint Identification Valid? Rhetorics of Reliability in Fingerprint Proponents' Discourse. Law & Policy, 2006; 28(1): 109-135
21. NAS, Strengthening Forensic Science in the United States: A Path Forward, 2009, pages 143-4
22. The Law Commission. Expert Evidence in Criminal Proceedings in England and Wales. The Stationery Office, 2011, LC325. Page 32 footnote 65. URL:
23. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999, pages 91-92
24. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999, page 93
25. For example in Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999
26. Ashbaugh, D. Quantitative-Qualitative Friction Ridge Analysis, 1999
27. See Chapter 19
28. ED_0005 page 73
29. Professor Champod 25 November page 41ff
30. ED_0005 page 18
31. ED_0005 page 19
32. Professor Champod 25 November page 41
33. EC_0001 - The Current Position of Fingerprint Evidence - A Literature Review. C. J. Lawless, I. C. Shaw and J. Mennell, School of Applied Sciences, Northumbria University (the literature review prepared for the Inquiry), pages 8-9
34. Professor Champod 25 November page 41
35. ED_0005 page 17