Dorsal knuckle crease pattern
: utility for forensic human identification

  • Katie Nicoll Baines

    Student thesis: Master's ThesisMaster of Science

    Abstract

    The aim of this project was to determine whether the dorsal knuckle crease pattern may be of value within the field of forensic human identification. This was examined through three phases of research. The primary phase of research attempted to classify the pattern of the skin creases overlying the proximal interphalangeal (PIP) joint of the left index finger. Initial sorting resulted in 11 classification groups that were then subjected to tests of inter-observer consistency. The results of these tests found that there was a high degree of overlap between the groups established, with only three classifications showing percentage agreements between all observers that might reach a level of forensic relevance (>80%). This provided the conclusion that some classifications may be of value, but they are limited to few individuals-which may of course be highly relevant for forensic individuation.

    The second phase of research sought to test the viability of a previously established tracing method, for superficial vein pattern analysis, for use in interpreting the dorsal knuckle crease pattern of the PIP joint. The method used Photoshop© to visualise the image and a graphics tablet and stylus to trace the crease pattern. The pattern was coded using a system of letters and numbers and a qualitative assessment of crease depth (deep or faint) was also recorded. Reliability and repeatability of this method was tested by performing intra and inter-observer consistency evaluation. This analysis was performed on a subset of the original sample (n=16). The resultant patterns were assessed for agreement and further analysed using one, two and three way ANOVAs. Results of these analyses showed that there was no significant difference between the repeat traces, showing high intra-observer consistency. It also demonstrated that the highest consistency was associated with the repeatability of tracing lines. There was no significant difference between males and females or the percentage agreement between repeat traces. This suggests that there is no difference in the observers’ ability to trace male or female patterns. Four different observers were used for the inter-observer consistency study, of differing levels of experience with image comparison. Similar results were found to the intra-observer consistency study: all observers were better at tracing lines than the other features considered. The results indicate that experience in image comparison may have a positive effect on the repeatability of tracing.

    Finally, following completion of the previous investigations, further analyses were undertaken to test the applicability of the method in situations closer to real-case scenarios. Additional images were taken, using a BlackBerry© 8250 camera phone, in order to perform a comparison between high and low quality images and the appearance of the crease pattern as a result of changing quality and also changing position of the PIP joint. There was found to be a significant difference between the percentage agreement values for deep and faint creases found in each comparison. This indicates that faint creases are lost with reduced image quality and changing position of the PIP joint.
    Date of Award2011
    Original languageEnglish
    SupervisorSue Black (Supervisor) & Xanthé Mallett (Supervisor)

    Keywords

    • Human Identification
    • Biometrics
    • Admissibility

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