Tan Yan Wen, Crystal, Sim Hui Ying, Yvonne, Chin Chin Lim, Chiew Yung Yang
78th Annual Meeting of the American Society of Questioned Document Examiners,
(Virtual) 10th Aug – 14th Aug
Company stamps are commonly used to authenticate official documents such as quotations, sales invoices, and employment or business contracts, or to demarcate an area on the document for a signatory to sign. Although the stamp is usually machine-made, there exists variation in the orientation and position of the stamp impression relative to other elements (e.g. printed text or border) on a document due to the act of stamping.
In cases where stamp impressions on reproduced documents appear to have the same orientation and relative positioning to the other elements (e.g. signatory line) on the document, the document examiner has to consider the following possible scenarios:
- cut-and-paste manipulation
- random chance match
- match from stamp impressions made by a person having the habit of orientating the stamp in a particular direction.
The preliminary findings from our previous research “The Evidential Value of the Orientation of Stamp Impressions in Tampered Documents” have shown that the probability of scenarios (b) and (c) for original stamp impressions made using a self-inking stamp are 0.1% and 4% respectively. This study further examines the probability of finding two reproduced stamp impressions with the same orientation and relative positioning to the other elements on the document. Factors such as the shape of the stamp die, stamp housing, and the presence of a signatory line will also be considered.