We are often asked if it is possible to establish the date on which a document was executed. Document dating is an involved process, requiring a sequence of steps beginning with non-destructive procedures and progressing to semi-destructive tests, if authorized. Due to the complexity of the issue, a detailed explanation follows.
When issues about a document's creation arise there are usually three questions that need to be answered. Have notations been added to an existing document? Have new pages recently been added to an existing file? Has the entire file been backdated or rewritten? Several approaches are used in our laboratory to address these questions. Analyses are performed by:
- Comparing the contested record to other similar documents from the same time frame.
- Intra-comparison of various entries in a file or document to assess whether they are similar or different.
- Reference to manufacturers and technical information held in our databases respecting the materials used to produce the document, such as paper, ink, type fonts, etc.
Comparison to Other Documents in a Record
1. Handwriting and Signatures
Individual handwriting characteristics evolve gradually over time. Although it is usually difficult to state exactly when a particular habit develops (except in cases of illness and possibly old age where the change is often quick and dramatic) we can date documents by comparison of the handwriting and signature habits.
To do this, samples executed over a long period of time, including the date in question, are needed. The contested signature or writing is then compared to a chronological sequence of the specimens.
2. Intersections
Entries made on the same document may be dated by analysis of intersections - areas where two or more pen lines cross. By analyzing these our document examiner may be able to determine the order of writing, possibly proving that a particular entry was added at a later time.
3. Pens and Inks
When dating documents it is sometimes necessary to determine whether one or more pens were used to write the material, or if the inks on the documents are the same.
Our document examiner begins with a variety of non-destructive tests for this purpose and proceeds to destructive tests if needed. Ink may be analyzed microscopically to determine pen and ink type, as well as colour. The unaided eye cannot differentiate between the dye components that make up a single colour. However, infrared examination conducted using a Video Spectral Comparator (VSC) may differentiate same colour inks by making visible any differences in their reflectant and luminescent components. This analysis is often effective for deciphering obliterations, detecting additions and distinguishing between a series of entries.
The examination of inks under IRL conditions relies on there being a component, or combination of components, present in the ink that absorbs incident light (excitation). This light, when re-emitted at a longer wavelength, produces luminescence. A VSC permits the observation of the emitted light in the infrared region. The IR portion of the examination looks at the reaction of ink to irradiation with a specific wavelength of light in the infrared region. This reaction can be observed using the VSC.
It cannot be concluded that only one ink is present when no differences are found using infrared excitation. The areas tested may be in the same ink, or they may be in different inks that react in a similar manner. If the IR and IRL analyses are inconclusive we may recommend testing with Thin Layer Chromatography (a semi-destructive analytical technique that allows for the identification of various dye components).
4. Paper
Paper is manufactured in a number of ways using different fibers, dyes and whiteners. These differences are relied on to distinguish and date paper. The size, shape and thickness, along with manufacturing watermarks, are analyzed macroscopically for similarities or differences. Other characteristics may then be examined microscopically with transmitted and reflected light.
The pages are compared using ultraviolet excitation to detect the presence of fluorescence. Differences in fluorescent qualities may indicate the use of different paper.
5. Typewriters
Typewriters can develop progressive defects (damaged type elements, poor alignment, and other mechanical flaws or imperfections) that provide a means for determining the approximate age of a typewritten document. These defects are particular to a machine and documents prepared on that machine should bear these marks. By studying adequate comparison samples we can determine the various 'first-date' appearances of the particular defects. The questioned text is then compared to the specimens to determine if, and where in the sequence, the defects appear. This analysis may establish whether or not the documents were executed on the purported date(s).
6. Photocopiers and Laser Printers
Photocopiers and laser printers can develop extraneous marks caused by dirt, malfunction or damage that may be an excellent source for dating documents. These trash marks, which can be transitory or permanent, develop over time with use and are unique to the machine. We will establish the time period when a defect occurred by analyzing first generation comparison samples. If the document in question is dated during that period and does not contain the trash marks it cannot have been produced at that time or must originate from a different machine. It may be found that the questioned document contains trash marks that are associated to defects that developed later than the date on the contested document. Ample comparison samples are required to establish that the questioned document was produced on a particular machine.
7. Facsimile Machines
A facsimile transmission bears a transmitting terminal identifier (TTI) at the top of the page. The TTI header should contain a combination of the transmission date and time, page number, and the name and telephone number of the sender and/or receiver. This information is programmable, which means that it can be changed or deactivated by the sender. The manufacturer, however, sets the typefont and formatting - features that are used to classify and identify a make and model.
A questioned facsimile document may be dated by comparison to known facsimile documents. We will determine if the TTI header matches the header on the contemporaneous samples and whether it is a digitized reproduction or an original image. If the font and formatting of the TTI header does not match the samples it may indicate that this document was fabricated.
Dating of Materials Used in the Production of the Document
Another document dating technique is to determine whether or not the materials comprising the document existed during the period in question.
We rely upon reference collections and information provided by the manufacturers of the material. The producers may have accurate records of the date of introduction, or changes to, their product. When the questioned document's date precedes the manufacturing date, it is established that the document could not have been prepared on the date it bears.
1. Paper (Watermarks, Bound Books, Ledgers, Diaries, and Logbooks)
The date can be verified if the manufacturer of the paper product is identified and will provide a record of the date of introduction or modification.
2. Letterhead and Printed Forms
We can detect a code or form number on a printed document and source it to the production and/or modification date. Letterhead will be examined for changes in design, wording, telephone numbers, addresses, or corporate logos that are inconsistent with the disputed document's date.
3. Typewriters
It is generally possible to identify the type-font and it's manufacturer. A thorough search of our reference materials and computer databases often reveals a date of introduction or design change.
4. Photocopiers, Dot-matrix Printers, Laser Printers, Ink-jet Printers and Facsimile Machines
Establishing date of manufacture or purchase of a machine can be another method of dating a questioned document. Research may prove that the model used was not yet on the retail market, or that the model was no longer, or not yet, in use in the office where it was purportedly used to produce the questioned document.
Other Ways to Date Documents
1. Indented Impressions
When writing on a piece of paper positioned on top of others, the writer often leaves non-inked indentations or impressions of that writing on the pages beneath. In our laboratory an Indentation Materializer(IMED) or Electrostatic Detection Apparatus (ESDA) is used to provide a visual image and record of these impressions, which appear as dark lines on a transparency. Analysis of intersecting impressions (the visible ink lines with the indentations) is often useful in dating documents because the order of entry may be determined. For example, the sequence of intersections may indicate that the entries were out of order, suggesting that information was added at a later date. This method of document dating can provide both relative and absolute dating information.
2. Offsetting or Ink Transfer
Offset marks occur when two or more pages of continuous writing are executed on the front and reverse sides of a sheet of paper in a bound ledger. When the writing on the reverse intersects with that on the front, ink may be transferred from the front page onto an underlying page. If this phenomenon is found on several differently dated pages, it indicates that the document was executed in a single sitting, not over time as suggested by the dates.