Lip and ear impressions and suspected bite injuries can be documented as observations, but appearance does not establish a validated unique-source method. The scientific limitations of bite-mark comparison on skin extend beyond merely rejecting absolute identification.
Prioritise appropriate medical care, consent, records and suitable biological sampling. Dental identification from remains is a different application from attributing a skin injury to someone’s teeth.
By the end of this topic you will be able to:
- Distinguish pattern documentation from source attribution.
- Explain the scientific limits of bite-mark comparison on skin.
- Coordinate injury records and appropriate biological sampling.
- Cheiloscopy
- Description and study of lip-print features, not demonstrated universal unique-source identification.
- Suzuki-Tsuchihashi classification
- A historical groove classification; classification is not individual attribution.
- Otoscopy (earprint)
- Here distinguish ear contact impressions from clinical ear examination; impression source claims need validation.
- Forensic odontology
- Dental science applied to legal questions; dental identification and skin bite comparison are distinct tasks.
- ABFO No. 2 scale
- A photographic reference scale whose placement must account for the injury surface and camera geometry.
- Class vs individual evidence
- Neither a class label nor a cautious phrase substitutes for a demonstrated scientific basis.
Cheiloscopy: The Lip-Print Fundamentals
Cheiloscopy describes lip-print features. Historical classifications do not establish lifelong stability, discrimination of every person or reliable source attribution from a partial deposit.
Lip-print classifications describe arrangements of visible grooves. The deposited pattern also depends on which part contacted the surface, pressure, motion and substances present. A neat reference impression and a partial scene smear need not provide comparable information.
Lifting and Developing Lip Prints at the Scene
Document the deposit and substrate before suitable recovery. Cosmetics, pressure, movement and development can alter represented features; coordinate possible biological sampling.
Earprint Examination and Its Limitations
Distinguish earprint examination from the clinical examination commonly called otoscopy. Ear contact impressions can vary with pressure, movement and surface; historical measurements are not universal identification criteria.
An ear contact impression is a surface-transfer observation. Ear shape, pressure and head movement influence what is recorded. A classification or measurement can describe an observation without demonstrating reliable individual attribution.
Suspected Bite Injuries: Documentation and Sampling
A suspected bite injury needs clinical assessment and careful documentation. Pattern appearance alone may not reliably establish that it is a human bite.
Use suitable photographs and scales with attention to curvature, camera geometry and changing injury appearance. Preserve potential saliva under appropriate clinical and forensic procedures.
Injury photographs should preserve body location and appropriate close views. The record should identify who photographed the injury, when, the surface condition and relevant changes during follow-up. Coordinate potential saliva collection with clinical care and applicable consent or authority.
Bite-Mark Comparison: Scientific Foundations and Limits
NIST’s scientific-foundation review identifies unresolved problems in recognising bites, skin recording of dental features and examiner performance. Calling an attribution “class” or “consistent with” does not resolve those foundational problems.
Do not infer reliable exclusion or inclusion merely from a tooth-pattern resemblance. Dental-record identification and DNA evaluation have separate methods and limitations.
NIST’s review separates several foundational questions: whether an injury is a bite, whether skin reliably records dental features and whether examiners can accurately associate those features with a source. Failure at an earlier step cannot be repaired simply by using cautious language at the final comparison step.
Six Anchor Questions on Minor Impression Evidence
Separate observation, biological examination and any proposed pattern interpretation. Explain the evidence base for each method and the question it can address.
Check Your Understanding
Sources
- 1.Trace evidence analysis · New Jersey State Police
- 2.Trace Evidence Recovery Guidelines (historical technical guidance) · SWGMAT; NIST host
- 3.Bitemark Analysis: Scientific Foundation Review · NIST