Thumb impressions appear on sale deeds, receipts, affidavits, wills and bank papers — especially those of persons who cannot sign. When one is disputed, it can be compared with specimen impressions of the person, often with a definite result.
Why fingerprints identify
- The ridges on the fingers and thumbs form before birth and do not change through life, except by injury that leaves a permanent scar.
- The arrangement of ridge details differs from person to person, and from finger to finger.
How the comparison is made
- Pattern — the general type of the impression: loop, whorl, arch or composite.
- Ridge characteristics — ridge endings, bifurcations, islands, short ridges and enclosures, and their position relative to one another.
- Agreement and disagreement — identity is concluded from sufficient characteristics in agreement, in the same relative positions, with no unexplained difference. Enlarged, charted photographs illustrate each point for the Court.
When an impression cannot be compared
A smudged, over-inked, faint or partial impression may lack enough clear detail. In that case the examiner says so plainly rather than give an opinion the material cannot support.
Specimen impressions
- Specimens are taken with suitable ink on smooth white paper — both rolled and plain impressions of all fingers, several times.
- They should be taken in the presence of witnesses, or under the direction of the Court.
- Where the person has died, earlier documents bearing admitted impressions — registered deeds, bank records — may serve as standards.
What to bring
- The document bearing the disputed impression (the original wherever possible).
- Specimen impressions, or documents bearing admitted impressions.
- Details of the proceedings, if a case is pending.
This article is general information, not legal advice. Each opinion depends on the impressions examined.