Collection, Identification & Comparison of Lip prints

How are lip prints collected, identified and compared in forensic cases?

1. COLLECTION, DEVELOPMENT, IDENTIFICATION AND COMPARISON OF LIP PRINTS Muthuraj V
Volunteer of AFRS

2. CONTENTS Introduction Collection of lip prints Development of lip prints Identification of lip prints Comparison of lip prints Application and limitations conclusion

3. INTRODUCTION Lip prints, also known as cheiloscopy , are unique patterns and characteristics found on the human lip surface. They are considered a valuable tool in forensic investigations for identification purposes. This presentation will discuss the processes involved in the collection, development, identification, and comparison of lip prints.

4. Collection of lip prints Lip prints can be collected using various methods: Lipstick Method: In this method, a subject applies a layer of lipstick or lip balm, then presses their lips onto a clean white or transparent sheet of paper. The lip prints left behind can be visualized and analyzed .
Lip Gloss Method: Similar to the lipstick method, lip gloss can be used instead of lipstick to create lip prints on a clean surface.
Lipstick Pad Method: A small pad or cushion soaked in lipstick or lip gloss is pressed against the lips, creating a clear impression that can be transferred onto a piece of paper.

5. Collection of lip prints Gelatin Method: A layer of gelatin is prepared by dissolving powdered gelatin in water and allowing it to solidify. The subject presses their lips onto the gelatin surface, leaving an impression that can be analyzed Cellophane Tape Method: In this method, a piece of clear cellophane tape is carefully pressed against the lips to lift the lip print. The tape is then placed onto a white or transparent surface for analysis.
Transparent Adhesive Method: A transparent adhesive sheet is applied to the lips and pressed gently. When removed, the adhesive sheet captures the lip print, which can be visualized and analyzed .
Dental Impression Material Method: Dental impression materials, such as alginate or silicone, can be used to create a mold of the lips. The mold can then be filled with plaster or dental stone to obtain a three-dimensional replica of the lip print.

6. Development of lip prints Once lip prints are collected, they need to be developed for analysis. Development methods include: Powder method: Powder is applied to the lip print and gently brushed off, leaving the print visible.Chemical method: Chemical substances, such as ninhydrin or iodine fuming, can be used to enhance the visibility of lip prints. Photography: Lip prints can be captured using specialized photography techniques, such as infrared or ultraviolet photography.

7. Identification of lip prints The identification of lip prints involves comparing the collected prints to known reference prints. Lip prints have distinct patterns, such as grooves, furrows, and wrinkles, which can be classified into different types based on their characteristics. Various lip print classification systems exist, such as Tsuchihashi’s classification, Suzuki and Tsuchihashi’s classification, or Santos’ classification. Computerized systems and software can aid in the identification process by analyzing and matching lip print characteristics.

8. Comparison of lip prints When comparing lip prints, examiners look for similarities and dissimilarities in the pattern and features. Points of comparison include: Overall shape of the lip print.Presence of unique features, such as scars, cuts, or deformities. Alignment and orientation of grooves and furrows . Comparison can be done visually or using automated systems, depending on the available resources and complexity of the case.

9. Application and limitations Lip prints are used in various fields, including forensic investigations, personal identification, and criminal profiling. They can provide valuable evidence in cases where other forms of identification, such as fingerprints, are unavailable or inconclusive. However, there are certain limitations to consider:Environmental factors and surface conditions can affect the quality of lip prints. Individual variations and changes in lip features over time can make identification challenging. Lack of standardized classification systems and databases may hinder comparisons across different cases.

10. Forensic application of lip prints Identification and Individualization: Lip prints, like fingerprints, have unique characteristics that can help identify and individualize individuals.
Linking Suspects to Crime Scenes: Lip prints found at a crime scene can establish a connection between a suspect and the location by comparing them to prints obtained from the suspect.
Evidence in Sexual Assault Cases: Lip prints can be crucial in sexual assault cases, as they can help identify the perpetrator through analysis of lip marks on the victim or other surfaces involved.
Disputed Document Authentication: Lip prints can be used to authenticate documents, such as wills, by comparing the lip print on the document to a known reference sample.
Timeline Estimation and Suspect Elimination: Lip prints can assist in estimating the timeline of events and eliminating suspects by comparing prints found at the scene with those of potential suspects.

11. Conclusion Collection, development, identification, and comparison of lip prints play a significant role in forensic investigations and personal identification. Proper collection techniques and suitable development methods are essential for obtaining clear and reliable lip prints. Lip print patterns and characteristics can be classified and compared to establish identification. Despite some limitations, lip prints offer valuable insights and can be a valuable tool in forensic science.

12. Reference Agarwal P, Bhatnagar G, Wadhwan V, et al. Lip prints: Role in forensic odontology. J Forensic Dent Sci. 2012;4(2):93-96. Sharma P, Saxena S, Rathod V. Cheiloscopy : The study of lip prints in sex identification. J Forensic Dent Sci. 2009;1:24–7. [Google Scholar] Prabhu RV, Dinkar AD, Prabhu VD, Rao PK. Cheiloscopy : Revisited. J Forensic Dent Sci. 2012;4:47–52. [PMC free article] [PubMed] [Google Scholar]
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