Cutting edge document examination: The physical fit of machine-cut edges of paper.

This technical note describes in detail a method for associating individual sheets of blank A4 white paper from the same ream by the physical fit of machine-cut edges. A large-scale laboratory trial involving ~700 sheets of paper from 24 different reams (plus one spoiled sample), and more than 20,000 potential physical fits, correctly associated and sequenced 219 pairs of sheets together with a 100% empirical success rate and no false associations. The edge profile of each short machine-cut end of a sheet of A4 paper allows us to physically fit sheets of paper from the same ream to each other and use this to predict the sequence of sheets in a set of documents. In a real-life scenario, it may now be possible to detect the substitution or addition of a sheet in a multipage document, link documents from different sources to each other or to a common source of paper (e.g. to paper from a seized printer or from an accused's address) or to date documents. The study provides data for the application of this method in forensic casework and supports the practitioner when forming conclusions in this type of case.

Exploitation of the Ultraviolet Properties and Machine Cut Edges of Paper to Associate and Sequence Sheets in a Ream.

Previously unreported line patterns visible under ultraviolet light were observed on a proportion of plain white A4 printer/copier paper from different manufacturers. These Ultraviolet Line Patterns (UVLPs) usually appear as stripes down the vertical length of the paper. Typically, the UVLPs were found to "repeat" through the ream in a predictable way, while also changing. It is postulated that the repeating nature of the UVLPs is a result of the way that paper is manufactured. This leads to the ability to sequence the sheets compared to their original source paper. Even in the absence of UVLPs, it is possible to use our observation of the manufacturing process to anticipate the order of several sheets of paper and conclusively associate them, in some cases, by physically fitting their machine cut edges and crossing paper fibers. Such a novel approach to examining questioned documents would be highly useful in forensic casework.