Examination of Indentations Produced by Photocopiers

Questioned Document Examiners analyze a variety of evidence. Although there are other methods of photocopier identification, one area that has not received as much investigation is the effect of the internal mechanisms of photocopiers on the paper processed through them. As paper is carried through the photocopier it interacts with feeding mechanisms which may leave indentations on the sample. These indentations can be visualized using an electrostatic detection apparatus. Using this method, samples representative of every possible pathway a piece of paper could take through a photocopier were collected for analysis from three photocopiers, a Canon imageRUNNER Advance 4251, a Canon imageRUNNER Advance DX 4751i, and a Canon imageRUNNER Advance C5560i. When samples from the same photocopiers were compared, those with enough detail visualized showed consistent similarities across samples, and a lack of dissimilarities. When samples from different photocopiers were compared, there were some visible similarities, but there were also noticeable differences. Additionally, several samples developed wide bands or stamp marks. These features also exhibited similarities and dissimilarities with those on other samples. Blind testing was completed, which supported the validity of this method. The results of this analysis suggest that the indentations produced by photocopiers is a viable method for use in questioned document analysis.