Board Certified Forensic Document Examiner specializing in handwriting identification and suspect documents.

Emily J. Will, D-BFDE

Introduction

Handwriting is only one aspect of the work of a forensic document examiner. With the aid of specialized devices, many hidden artifacts become visible. The equipment enables the examiner to see things, but it is knowledge and experience that allow the examiner to interpret the findings correctly and to understand any limitations in the specific case at hand.

The most important tool a document examiner has is his or her own vision, but in this section and the laboratory tour section we will consider the external tools which enable the examiner to see, evaluate and record more than is apparent to the unaided eye. Forensic Document Examination is a field with many subsets, as explained on the Applications page. Technology and instrumentation are a great aid to the document examiner. Magnifiers and Microscopes make small details visible and measurable. Combining those devices with cameras allows the examiner to study and compare images and to present illustrations to clients and fact-finders. A variety of specialized light sources extend the examiner's eyes into portions of the electro-magnetic spectrum where they can not go unaided. The most useful areas of the spectrum for the document examiner are the Ultraviolet and Infrared wavelengths, which allow the differentiation of similar appearing inks and the review of normally invisible security features. And, speaking of invisible, EDD (electrostatic detection device) equipment reveals and demonstrates "indented writing."

Magnifiers

Several years ago I purchased an illuminated magnifier at an auction. It was a useful tool, providing its own light and 4 power magnification. One day, when trying to photograph a document under difficult lighting conditions in a court clerk's office, I put my camera on top of the illuminated magnifier. Wow! I was delighted to learn that by resting the 35mm camera with its smallest extension tube on top of the illuminated magnifier I could capture an excellent image.

Eventually I purchased a digital camera and tried the camera with the magnifier. And again it was a perfect match. This might not work with every digital camera. The one I use has a 10X optical zoom resulting in a lot of flexibility.

With these discoveries, my illuminated magnifier became the most used item in my arsenal of equipment. Document examiner friends asked where to get one like it. I did an Internet search. After a web visit and some in-depth phone conversations, I ordered a range of products which are manufactured in Germany by Eschenbach.

Everything that you see here has been tested in my office and found to be useful for document examination. Of course, if you are a stamp or coin collector, electronic assembler, or just like to examine life closely, you will find these products interesting. Please feel free to call 919-556-7414 or email me with your comments or questions. And remember that if a picture is worth a thousand words, a well-lit, magnified image speaks volumes.

Shedding Some Light on Your Document Problems

The illuminated magnifier I use so much is actually part of a system of illuminated magnification products by Eschenbach. There are several types of magnifiers available. A stand magnifier is excellent for any type of work because the magnifier body is its own stand. Your hands are free for other tasks.

Illuminated stand magnifiers have two parts - the head and the handle. The head is a circular or rectangular unit which consists of a housing and the magnifying lens. I prefer the round head because camera lenses are round. There are heads available at several magnifications (3X, 4X, 5X, 6X, 7.5X, 10X, 12.5X).

According to the laws of optics, as magnification increases, the field of view decreases. Also, as powers of magnification increase, there is some distortion as you look away from the center of the lens. Eschenbach minimizes this distortion by using a lens with aspheric curvature. But the price of using an aspheric lens is that the eye must be at a specific working distance from the lens to avoid the distortion.

After a thorough examination of the various lenses available, the ones I find most useful are 4X and 7X. The 4X head has a comfortable working distance and a useful field size. With either a 35 mm camera plus extension ring or a digital camera plus zoom, the 4X yields good detailed photos. For those situations where a closer image is needed, the 7X head is my choice. The heads are fully interchangeable. No matter what handle you decide on, any head will match. If you have several heads and just one handle, and the net result is that you have several magnifiers. The images be low were taken with increasingly stronger magnifiers - 4X, 7X and 10X.

The second part of the magnifier is the handle. The handle is designed so that when it is connected to the head the entire unit will lie flat on a table to form its own stand. Three types of handle are available: an incandescent battery handle, and a halogen handle, and an LED handle. The bulb types are NOT interchangeable on the handles. The electrical assemblies of the handles are specific to the type of bulb.

A halogen bulb is whiter, brighter, and draws more power than an incandescent bulb. This need for power is the reason that the halogen handle sports a 110-120V power cord. There is actually another option - a halogen battery handle, but it is suggested that it be purchased as a companion to the plug-in handle for use only in special situations. It requires three C size batteries which last approximately three hours.

The incandescent battery handle requires two C batteries which last much longer. Rechargeable batteries can be used in either handle.

The LED handle has the advantage that the LED lamps should not need to be replaced (whereas bulbs burn out and need periodic replacement), and the battery life is extended. However, for document examination, there is no IR content in the illumination, and therefore the LED magnifier is not useful for use with IR filters.

The top unit is an incandescent battery halogen handle with a 7X head. Below that is a halogen pulg-in handle with a 4X head. Notice the wider field and less distorted image through the 4X head at this working distance (approx. 18 inches). Also note the different colors of light. The rheostat on the halogen handle is set for full power.

To summarize, my personal favorites are the 4X and 7X heads. I now own both and select one to use depending on whether fine detail or breadth of field is more important in what I need to see/photograph. If you are purchasing one handle only, consider a plug-in halogen. I find the halogen bulb to be more enlightening - both for the eye and for the camera.

A battery handle is great to have in certain circumstances. You can economize by selecting an incandescent, or you can select a battery halogen if you prefer the brighter light.

Additional Useful Tools
If you need to make careful, distortion-free measurements, Eschenbach offers Precision Scale Magnifiers that accept interchangeable measuring scales. The Precision Scale Magnifiers are available at 7x and 10x. The 7x is most versitile for document examination. Each unit has a clear plastic base which allows light into the field. An option is to combine the unit with an adaptive head that allows the scale magnifier to be used with any of the illuminated handles. Several scales are available. My two favorites are the linear scale and the combination scale. This 7X Precision Scale Magnifier (right)is fitted with a linear scale that is marked in tenths of a millimeter. The combination scale offers several useful measurement options.

Why Eschenbach?
Eschenbach is a German company that has been manufacturing precision optics for over 80 years. Eschenbach producst are carefully designed and engineered to be easy and comfortable to use. Each feature has been maximized for its purpose.Lenses are manufactured from a proprietary compound, PXM®, which has the same optical qualities as glass, but is lighter and more resistant to breaking. Together with the Frauenhofer Institute for Silicate Research, Eschenbach has developed a new coating for the PMX® lenses called cera-tec® which significantly improves scratch resistance. When ANSI (American National Standards Institute) decided to publish standards for Magnification, Eschenbach was on the development team. If you appreciate good tools, you will enjoy working with any Eschenbach product.

Contact:
Emily Will
P.O. Box 58552
Raleigh, NC 27658
Ph: 919-556-7414
Email: ewill@Qdewill.com

Microscopes

Document examiners use a wide range of magnification equipment. Handheld magnifiers enlarge the material from 2 to 10 times (magnification powers of 2x to 10x) and may have lighting abilities as well to brighten the field of view. To see details more closely, there are many types of microscopes. A binocular, or stereo, microscope is comfortable to use because, as the name implies, there are 2 eyepieces and the viewer focuses with both eyes. In addition, a microscope can have a third viewing tube which allows a still or video camera to be attached for "through the microscope" photography or videography. Digital microscopes combine optics for magnification with digital capture technology to allow the user to view the magnified image on the monitor instead of or in addition to viewing it through the microscope eyepieces. Specialty microscopes, such as a document comparison microscope, preform additional specific tasks.

It might seem that the more powerful the microscope in terms of magnification, the better, but for the task of handwriting examination, this is not the case. Most handwriting examination is done at powers of 10x to 50x (the subject is enlarged 10 to 50 times). When magnification is higher, the field of vision is so narrow that the object viewed loses relevance. In this example, my signature is shown at 10x, 15x, 20x and 25x.

It is a good idea to start out with a low power when first examining a portion of a document and then to zoom in closer to the area you want to inspect.

A type of microscope that is particularly useful in document examination is the comparison microscope. Two documents can be viewed side-by-side and the images can be positioned so that they appear to overlay each other. By using a different color of filter on each document, the examiner can then see a third color in those areas where the two segments being compared overlap each other. Below you see the results when two of my signatures are viewed under the comparison microscope at 15x. The interplay of colored light makes this image a bit confusing to the first time viewer, but essentially you are seeing a composite of two signatures (one viewed through a red filter and one viewed through a green filter) in which the black line segments are the places where the two signatures would coincide if the signatures were really on top of each other.

One enjoyable fringe benefit of being a document examiner is recreational use of the microscope. Over the years I have looked at and photographed lots of interesting things through the looking glass. Below are 6 reasonably common items photographed at varying powers. See if you can discern what they are. To check your answer, hover your mouse over each image.

Infrared/Ultraviolet

A special instrument for document examination is a UV/IR spectral comparator which makes use of electromagnetic wavelenths and various filters to differentiate inks and reveal hidden material on documents. The Foster & Freeman VSC-4c has a full compliment of visible, UV and IR sources, source and camera filters, coaxial light, transmitted light, oblique light and other features that allow the document examiner to see beyond what the human eye can see. For example, in the case above, a report of a traffic accident contained an obliteration. Using the VSC, the underlying writing could be read and photographed.

This demonstration parallels many cases in which additions to documents can be detected by the use of Infrared absorption or luminescence examination.

Ultraviolet examination is also useful in the examination of documents. Here, UV reveals fluorescent security fibers embedded in the paper of many currencies. There are many other types of examinations possible with spectral comparators. Discuss your case with your document examiner to see whether there might be more to the document than meets the eye. Spectral comparators similar to the VSC are made by Projectina and ACO Electronics.

Indented Writing

Sometimes special situations call for special instruments, such as an electrostatic detection device which is used to detect indented writing. The photo (left) shows an ESDA-lite by Foster & Freeman which consists of a metal box with a porous metal plate at the top. The document is positioned on the plate and covered with a clear protective sheet. A vaccuum is drawn, holding the document tightly to the metal plate, and an electrostatic charge is transferred to the document.

Next, a special toner powder is sprinkled over the protected document and the toner is drawn into the indentations on the document, making them visible. If indentations are revealed the results can be photographed. The toner is sandwiched between plastic and does not touch the paper.