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Cheiloscopy classifications, the Iannarelli earprint system, and the bite-mark debate after NAS 2009, written for FACT § 6.4 and Indian SFSL practice.
Lip prints, earprints and bite marks sit at the edge of pattern evidence. Each is a body-derived impression that imprints on a surface, each has a classification system that looks more confident than the underlying biology supports, and each has been pulled into Indian appellate reasoning at least once. The three together form FACT § 6.4's "minor impression evidence" group, and the NFSU practical viva treats them as a single comparative cluster: you should know how to lift each, what classification systems exist, and where the courts have pushed back.
The honest framing is that this is class evidence wearing individual-evidence clothes. The Suzuki-Tsuchihashi lip-print classification, the Iannarelli earprint measurements, the ABFO bite-mark scoring all produce categorical labels that sound discriminating. The 2009 US National Academy of Sciences report and a decade of Indian appellate scepticism that followed have pushed the field to admit that uniqueness has not been demonstrated, sample sizes are small, and population frequency data is mostly absent. That doesn't mean these tools are useless. It means a candidate who answers "lip prints are unique" in a 2026 NFSU paper is repeating a textbook line the examiner already knows is contested.
Snyder 1932, Suzuki-Tsuchihashi 1970, and the patterns the viva asks for.
The lip's free border (the vermilion zone) carries a pattern of grooves called sulci labiorum. Snyder's 1932 textbook Homicide Investigation was the first English-language work to argue these grooves could be used for identification, although the underlying observation was Locard's. By the 1970s the Japanese researchers Suzuki and Tsuchihashi had surveyed enough lip-print samples to propose the five-type classification still used today.
A few facts the viva keeps returning to. Lip prints are stable across adult life unless trauma or disease (cheilitis, herpes labialis scarring) alters the surface. The pattern is laid down during the third intrauterine month. Identical twins show similar but not identical patterns, which is the strongest argument the field has for some discriminating power. Population studies from Indian samples (a much-cited 2014 Chandigarh study; AIIMS Delhi work in 2019) report Type II and Type III dominate among north Indians, with regional variation that has been used to argue for population-specific reference databases.
The Indian SFSL practical reality is more modest. Lip-print evidence appears in casework as one circumstantial strand alongside DNA, fingerprints and CCTV. No published Indian conviction rests on cheiloscopy alone, and the cases that get cited (Karnataka glass-marked-with-lipstick robberies; a few Mumbai sexual-assault matters) all had corroborating physical evidence. Cross-link to Forensic Photography for the documentation grade that lip-print photographs need.
Cup, cigarette butt, glass rim. The substrate dictates the method.
The collection workflow is substrate-dependent. Most lip prints recovered in Indian casework come from drinking glasses, tea cups, cigarette butts, bottle rims, envelope seals and the occasional kissed letter. Each surface needs a different development method.
Iannarelli's 12 measurements, and why you almost never see this in court.
The earprint is the rarest of the three. The external ear is anatomically complex (helix, antihelix, scapha, triangular fossa, tragus, antitragus, lobe) and the cartilage is firm enough that when a person presses an ear against a door or window during eavesdropping or forced entry, an oily latent print transfers in a way that captures most of those features.
Alfred Iannarelli proposed a 12-measurement system in 1989 based on a sample of around 10,000 ears. The measurements are pair-wise distances between the seven anatomical landmarks shown above. He argued the combined measurement set could discriminate at near-individual level. The trouble is that the sample was self-selected, the measurement protocol depended on operator skill, and reproducibility studies in the 2000s (the European FearID project, finished 2006) found inter-examiner agreement of only around 90% on the most discriminating measurements.
Compression, suction, abrasion. Photograph at 90° with ABFO No. 2.
Bite marks are the most common of the three impression types in violent-crime casework, especially in sexual assault, child abuse and homicide. A bite mark is a patterned injury where the dental arch indents skin, food, chewing gum, a cigarette filter or similar deformable substrate. The forensic odontologist works from the photographed pattern back to a possible source dentition.
The on-scene collection workflow has been stable for two decades.
Why bite marks are now formally class evidence.
The American Board of Forensic Odontology published a scoring scale in 1995, updated several times since, that asks the examiner to grade the degree of similarity between the bite pattern and the suspect's dentition on a graduated scale (from "exclusion" through "inconclusive" to "the biter").
| Era | Mainstream odontology claim | What changed | Indian appellate reception |
|---|---|---|---|
| 1970s to 1990s | Bite marks can identify an individual to the exclusion of all others | Casework conviction based on bite-mark testimony alone (US: Bundy 1979; UK: various) | Limited Indian casework; bite marks treated as corroborating evidence only |
| 2000s | Bite marks discriminate among a small group of suspects | Population-frequency studies failed to demonstrate uniqueness; several US exonerations on DNA review | Mohammad Aman v State of Rajasthan (2017) admitted bite-mark evidence but stressed corroboration |
| 2009 to 2016 | Bite marks are class evidence; identification claims are not scientifically supported | NAS 2009 report; PCAST 2016 report; multiple US state courts limit bite-mark testimony | Indian SFSLs adopt the conservative ABFO scoring; cross-examination routinely challenges uniqueness claims |
Six questions that come back every year.
The viva for this section is predictable. The examiner is testing whether you understand the three impression types as a class, can list the standard development and lifting methods, and can answer the uniqueness question without overselling.
In the Suzuki-Tsuchihashi lip-print classification, which type is characterised by a net-like (reticular) pattern of grooves?
The Indian SFSL anchor here is the standard kit issued to state SOCO teams: magnetic powder, aluminium powder, ABFO scale, an envelope set for cigarette butts and a small lip-print reference pad. State FSLs in Gandhinagar (NFSU campus), Hyderabad and Madhuban have all published kit lists that include these items as routine.
Indian SFSL casework with earprints is rare. The scenarios where it has been attempted include burglary cases where the suspect pressed an ear to a glass door, and one widely-cited Maharashtra case where a kidnapping suspect's ear had imprinted on a bound victim's clothing. In both, the earprint was offered alongside fingerprint and DNA evidence and was not the deciding strand. The NFSU syllabus retains otoscopy as a teaching unit, but the practical viva tends to test recognition (can you label the seven landmarks?) rather than identification math.
The "bite on victim vs bite on perpetrator" question is asked in nearly every NFSU viva. The short answer: a bite on the victim is the suspect's dentition (offensive bite, often during an attack); a bite on the perpetrator is the victim's dentition (defensive bite, often during resistance). Both are documented identically. The investigative significance differs.
| 2017 to 2026 | Bite marks help include or exclude classes of dentition; DNA from saliva is the primary identification route | Salivary DNA recovery becomes the standard first step on every bite mark | Indian appellate practice treats pattern-only bite-mark testimony as inadequate; DNA corroboration is now expected |
The 2009 National Academy of Sciences report Strengthening Forensic Science in the United States was the inflection point. Its bite-mark chapter concluded that "the scientific basis is insufficient to conclude that bite-mark comparisons can result in a conclusive match." The 2016 PCAST report repeated the finding more bluntly. Several US convictions that had rested on bite-mark testimony alone were vacated on DNA review, and a working group of US odontologists publicly walked back the uniqueness claim in 2018.
The Indian appellate response has tracked the international shift without ever fully embracing it. In Mohammad Aman v State of Rajasthan (2017), the Rajasthan High Court admitted bite-mark evidence but stressed that the testimony was corroborative, not the primary identification. The judgment is now the standard citation when bite-mark admissibility is in dispute. The SFSL practice that has emerged in Gujarat, Maharashtra and Tamil Nadu is conservative: photograph, swab for DNA, document, report patterns as "consistent with" or "inconsistent with" the suspect's dentition, and never claim individual-source identification on pattern alone. Cross-link to Chain of Custody because every bite-mark swab fails in court the same way every other DNA swab fails, on a broken custody chain.