Cheiloscopy (Lip Prints) in Forensic Identification: A Review
Dr. Madhura *1, Dr. Rashmi 2
*Correspondence to: Dr. Madhura. Department of Oral Pathology and Microbiology, Tatyasaheb Kore Dental College and Research Centre, New Pargaon, Kolhapur.
Copyright.
© 2026 Dr. Madhura, This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 25 July 2026
Published: 01 August 2026
DOI: https://doi.org/10.5281/zenodo.21715032
Abstract
Cheiloscopy, the study of the pattern of grooves and wrinkles on the vermilion border of the human lip, has been explored for over a century as a supplementary method of personal identification in forensic practice. Lip patterns are believed to be established during intrauterine development and to remain stable through life, a property that underlies their proposed forensic value alongside fingerprints and DNA. [1] This review summarises the history of cheiloscopy, the classification systems used to describe lip print patterns, the methods available for recording and enhancing lip prints from crime scenes and study participants, and the principal forensic applications of the technique, including personal identification, sex estimation, and disaster victim identification. The review also addresses the methodological limitations that currently restrict the evidentiary weight of cheiloscopy, notably the absence of a standardised recording protocol and mixed evidence for sex determination accuracy, and outlines directions for future research, including digital and computational approaches to lip print analysis.
Keywords: cheiloscopy, lip prints, forensic identification, forensic odontology, sex determination, personal identification.
Introduction
Identification of an individual is a central objective of forensic investigation, whether the context is a criminal case, a mass disaster, or a paternity dispute. Fingerprints, dental records, and DNA profiling remain the primary tools of human identification, but each has situations in which it cannot be used — for example, when a perpetrator wears gloves or when biological material is degraded. Cheiloscopy, derived from the Greek words cheilos (lips) and skopein (to view), refers to the forensic study of the patterns formed by grooves on the labial mucosa, generally called lip prints. [2]
Interest in lip prints as forensic evidence stems from the observation that criminals who take precautions against leaving fingerprints frequently leave lip impressions on glasses, cups, cigarette butts, tissue paper, or correspondence at a scene. [1] Because lip prints can be recovered from such everyday objects, and because the pattern of grooves is proposed to be as individual as a fingerprint, cheiloscopy has been studied as a low-cost, non-invasive adjunct to conventional identification methods.
Historical Background
The biological description of grooves on the red portion of the human lip is generally credited to the anatomist R. Fischer, who documented the phenomenon in 1902. [3] The idea that these patterns could serve a forensic identification purpose was proposed later: Le Moyne Snyder discussed the individuality of lip patterns in his work on homicide investigation, and the French criminologist Edmond Locard advocated the forensic use of lip prints in 1932. [3] [4] A systematic approach to classifying lip print patterns was introduced by the Japanese researchers Kazuo Suzuki and Yasuo Tsuchihashi, who examined lip groove patterns in a large Japanese population and, in 1970, proposed the six-category classification system that remains the most widely used scheme in cheiloscopy research today. [5] Subsequent decades saw the FBI and other agencies acknowledge lip prints as a potentially individualising feature, and interest in the subject has grown steadily, spanning forensic odontology, anthropology, and more recently biometric engineering. [4]
Biological Basis: Uniqueness and Permanence
The grooves and furrows that make up a lip print are thought to begin forming around the sixth week of intrauterine life and, once established, to remain unaffected by ageing, minor trauma, infection, or climatic conditions, remaining stable throughout an individual's lifetime. [6] [7] This claimed combination of individual distinctiveness and permanence is the biological basis for treating lip prints as analogous to fingerprints, and studies have reported that even the lip patterns of monozygotic twins, while broadly similar, are not identical in fine detail. [8] It should be noted, however, that the population-level uniqueness of lip prints has not been established with the same rigour as fingerprint individuality, and this remains a recognised gap in the underlying evidence base. [9]
Classification Systems
Several classification systems have been proposed to standardise the description of lip print patterns, including those of Martin Santos, Suzuki and Tsuchihashi, Renaud, Afchar-Bayat, and Domingo. Of these, the Suzuki–Tsuchihashi system is by far the most widely applied in the literature. [5] [10]
This system divides lip groove patterns into six types based on the shape of the grooves observed: Type I, a clear, long vertical groove running across the whole lip; Type I′, a shorter vertical groove covering only part of the lip; Type II, a branched or Y-shaped groove; Type III, an intersected or criss-crossed groove; Type IV, a reticular or rectangular grid-like pattern; and Type V, any pattern that does not fit the preceding categories, including irregular patterns. In practice, the lip is typically divided into four quadrants (upper right, upper left, lower left, lower right) and the predominant groove type in each quadrant is recorded. [11] [5]
Later authors have proposed refinements, including a ten-quadrant scheme by Kaur and Thakar that groups patterns into basic and combination categories, designed to allow classification of even partial lip prints recovered from a crime scene. [12] The variety of competing systems, and the fact that most were developed for the lipstick-and-tape method rather than for high-resolution digital images, is one of the standardisation issues discussed further in Section 7. [13]
Methods of Recording Lip Prints
A range of techniques has been described for recording lip prints, both from living study participants and from surfaces at a crime scene. The choice of method affects the clarity of the print and, in some studies, the apparent distribution of pattern types, so awareness of these techniques is important when interpreting or comparing published data. [14]
This remains the conventional and most widely used method. A layer of lipstick is applied evenly to the lips, which are then pressed onto cellophane tape or directly onto white bond paper; the tape is subsequently mounted on a contrasting background for examination, often with a magnifying lens or after scanning. Variants use coloured lipstick, lip rouge, or other transfer media, and some studies apply the lips directly to the paper without an intermediate tape-lift step. [15] [16]
When lip prints are left at a scene without a coloured transfer medium — for example on a glass, mirror, or window — they are latent and must be developed, much like a latent fingerprint. Reported approaches include dusting with conventional fingerprint powder or magnetic (Magna Brush) powder followed by lifting with tape, and photographing prints directly on non-porous surfaces such as mirrors, with the image enlarged and the grooves traced for analysis. [17] [18] A recent methodological review notes that, unlike fingerprint development, latent lip print enhancement techniques on both porous and non-porous substrates still lack a standardised, validated protocol, which limits their routine use in casework. [18]
More recent studies have used digital photography of the lips, with or without lipstick, as an alternative to the tape-lift method, arguing that high-resolution images preserve finer groove detail and avoid distortion introduced by pressure or lipstick thickness. Comparative studies report that digital photography agrees only moderately with the conventional lipstick–tape method and can yield a different distribution of Suzuki–Tsuchihashi types, which the authors attribute to the greater detail visible in digital images and to the fact that the classification system was originally designed around the coarser tape-lift image. [19] [20] Photographs are commonly analysed with general-purpose image-editing or measurement software to standardise contrast and grayscale before classification. [21]
Where a lipstick smear rather than a groove pattern is recovered, chromatographic techniques (such as thin-layer or gas chromatography) have been used to compare the chemical composition of the residue with a suspect's lipstick, offering a complementary line of evidence distinct from pattern-based cheiloscopy. [22]
5.5 Newer computational and biometric approaches
Outside forensic casework, lip texture has also been investigated as a biometric trait for automated authentication. Recent computer-vision work models the fine wrinkle and groove texture of the lips, and even the dynamic movement of lip articulation, as a basis for continuous identity verification, reporting that lip-texture features are relatively robust to lighting changes and the presence of cosmetics compared with colour- or shape-based facial features. [23] Bifurcation-based automated recognition algorithms and machine-learning classifiers have similarly been proposed to reduce the subjectivity of manual Suzuki–Tsuchihashi scoring, though these remain largely at the research stage rather than validated for court use. [23] [13]
Forensic Applications
The principal proposed use of cheiloscopy is comparative identification: a lip print recovered from a scene is compared against a known print from a suspect or victim to support or exclude a match, in the same conceptual manner as fingerprint comparison. Lip prints have most often been discussed in the context of violent crime, burglary, and sexual assault, where lip contact with glassware, cigarette butts, or skin is common. [1] [9]
Numerous population studies have examined whether particular Suzuki–Tsuchihashi types occur more frequently in one sex, with the general — though not universal — finding that vertical groove patterns (Types I and I′) are reported more often in females and branched or reticular patterns (Types II–IV) more often in males, allowing narrowing of a suspect pool by probable sex. [24] However, a systematic review and meta-analysis following PRISMA methodology, pooling studies published between 1982 and 2019, concluded that the diagnostic accuracy of lip print analysis for sex estimation is low and that the certainty of the underlying evidence is weak, cautioning against over-reliance on cheiloscopy alone for sex determination in casework. [9]
Lip print patterns have also been studied for potential use in disaster victim identification and in exploring familial or ancestral inheritance patterns, with some studies reporting a degree of resemblance in lip print type between parents and offspring and variation in pattern distribution across ethnic groups, suggesting a partly genetic influence on lip groove morphology. [2] [25]
Because cheiloscopy is a comparatively young and less standardised discipline than fingerprint or DNA analysis, its admissibility as courtroom evidence varies by jurisdiction and is generally treated as corroborative rather than conclusive. Authors reviewing this issue emphasise that consistent protocols for collection, preservation, and comparison are prerequisites for cheiloscopic evidence to be given greater evidentiary weight in judicial proceedings. [26]
Limitations and Critical Appraisal
Despite decades of research, several methodological limitations continue to constrain the forensic use of cheiloscopy. First, there is no single internationally accepted protocol for recording lip prints, and different recording media (lipstick-tape, bond paper, digital photography) have been shown to yield different apparent pattern distributions in the same individuals, complicating comparison across studies. [19] [18] Second, the population-level uniqueness of lip prints — the central premise of the technique — has been asserted more often than it has been statistically demonstrated across large, diverse samples. Third, as the systematic review discussed in Section 6.2 highlights, the evidence supporting sex determination from lip prints is currently assessed as weak, and many primary studies in the field have been criticised for small sample sizes and inconsistent classification methodology. [9] Fourth, most existing classification systems were designed for the coarser detail visible with the lipstick-tape method and may need revision to make full use of the finer detail captured by modern digital photography. [19]
Future Directions
Future work in cheiloscopy is likely to benefit from: development and validation of a standardised recording and enhancement protocol comparable to fingerprint development standards; large, multi-ethnic population studies to test the statistical uniqueness of lip print patterns with rigorous methodology; integration of digital imaging with computational pattern-recognition or machine-learning classifiers to reduce inter-observer subjectivity; and continued research into the biological basis of lip groove formation to clarify the extent of genetic versus environmental influence on pattern development. [23] [9]
Conclusion
Cheiloscopy offers a simple, low-cost, and non-invasive supplementary tool for personal identification in forensic practice, supported by a long history of case reports and population studies. At the same time, the current evidence base has clear limitations — most notably the lack of a standardised recording protocol and modest diagnostic accuracy for applications such as sex determination — that mean lip prints are best regarded as corroborative rather than stand-alone forensic evidence. Continued methodological standardisation and rigorous, adequately powered research will be needed before cheiloscopy can be used with the same evidentiary confidence as fingerprint or DNA analysis.
References