Medical identifiers: implants, scars, tattoos and radiographs

What it is

Medical findings are a group of identifiers that compare what is found on the body with what the medical records say. In INTERPOL's disaster victim identification guide they are secondary methods, except that unique serial numbers on pacemakers and prosthetic implants are considered reliable. Useful findings include scars from surgery or injury, healed fractures, bony deformities, missing organs, skin tumours, hernias, piercings and tattoos. Radiographs taken in life are especially valuable because they can be compared with postmortem imaging: the shape of a healed fracture, a plate and screws, or the bone pattern itself. Several secondary findings together may be enough to identify in some cases, but usually they guide the comparison by fingerprints, teeth or DNA. The ranking of all methods is on the identification methods page.

Accuracy and limits

• Serial numbers only identify if the hospital's or manufacturer's records can be traced.
• A common feature (an appendectomy scar) supports but does not identify.
• Radiographic comparison needs images taken in similar projections.
• Personal effects (documents, jewellery, clothing) may not belong to the body they are found with.
• Firmly attached jewellery (piercings, embedded rings) is of more value than loose items.

What it is based on

• An implant is manufactured with a serial number that the hospital records in the patient's file.
• Bone keeps the trace of old fractures and surgery for life.
• Radiographs show internal features that do not change after death, so they can be compared directly.

How it is applied

1. Describe and photograph every scar, tattoo, piercing, deformity and sign of surgery during the external examination.
2. Take X-rays or CT of the whole body to look for implants, old fractures and other features.
3. Remove implants when needed, record the manufacturer and serial number, and keep them under chain of custody.
4. Have a pacemaker read by a technician, or remove it and send it for reading.
5. Ask the authority to obtain the medical records and radiographs of the presumed person.
6. Compare antemortem and postmortem data feature by feature, with a radiologist or anthropologist if needed.
7. Report the degree of match and recommend a primary method if it is not yet confirmed.

Next step: what to do and document

• Record all medical devices, scars and surgical findings during the autopsy, even if they seem common.
• Remove pacemakers before cremation: they can explode in the fire.
• Ask relatives, through the authority, for the treating hospital and the medical and dental records.
• Do not issue identity on tattoos or personal effects alone.
• Hand over implants and their records under chain of custody.

Common mistakes

• Not taking X-rays of an unidentified body and missing implants or old fractures.
• Calling an identification positive from a tattoo or clothing alone.
• Discarding an implant without recording its serial number.
• Comparing radiographs taken in very different projections.

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Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.

Sources: Disaster Victim Identification Guide, Annexure 8: Methods of identification (INTERPOL, 2023); The Minnesota Protocol on the Investigation of Potentially Unlawful Death (2016) (Office of the United Nations High Commissioner for Human Rights, 2017).

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