1. Computer printouts and fax
Compare markings on a QD to an exemplar
Transitory patterns may arise from debris and other materials
TTI- tranmitting terminal identifier- on top of each fax page is in a different font determined by the sending machine and type set from text.
Alterations detected if TTIs reveal significant characteristics distinguish it from genuine TTI
TTIs number of characters, style, position in the header can all be evaluated through comparison to a collection of TTI font database maintained by the ASQDE

2. Differences Observed in Fax Lettering as Wear Increases

3. Class characteristics of printouts
Printing technology, type of paper and toner
Toner chemical composition
Type of toner to paper fusing method
Microscopic and ID of organic and inorganic components of toner
Results compared to databases on types of machines
Narrow down to manageable number for subsequent comparison to exemplar printouts

4. Model determination based on printouts
Requires extensive analysis of printer tech and type of ink used
Impact or non impact printers
Non-impact include ink-jet and laser printers
Impact type include thermal and dot matrix printers
All have characteristic ways of printing with shapes, toner differentiation and applications easily determined with low power microscope to narrow possibility of model type

5. Alterations, Erasures and Obliterations
Common erasures include india rubber eraser, sandpaper, razor blade or knife obliterations
Disturbance of upper layer of fibers on paper detected with microscopy using direct or oblique lighting
Chemical erasures use oxidizing agents on ink – detected by discoloration on treated area
UV or IR can reveal chemically treated portion

6. Infrared luminescence
Some inks reradiate IR known as IR luminescence
Differences in the luminexcent properties of the inks observed if altered
Can also be used to reveal writing that has been erased as invisible residues of writing may remain in paper
Also differences exist in ability of inks to absorb IR. Distinguish inks of dissimilar chemical composition

7. Obliteration
Intentional obliteration - overwriting or crossing out : seldom used for fraudulent purposes as it is obvious
Same ink- difficult to tell from original
If two inks are different photo with IR sensitive filme may reveal the original writing.

8. IR Device Used for Questioned Document Analysis

9. IR photographic detection of obliteration

10. White Out Obliteration

11. Case File: Obliterated Address
Top image: normal lighting
Middle image: reflected infrared
Bottom image: infrared luminescence
In this case example, the different spectral properties of the inked typewriter ribbon and the pen ink are exploited using infrared filters and various types of incident illumination.
TOP: normal light; shows pen ink was used to obliterate name and address and add a new name/address
MIDDLE: by using an IR filter, the pen ink is transparent and the original info is visible
BOTTOM: using blue light as the incident light on the address, the pen ink fluoresces and you can see the ribbon ink at the same time

12. Charred documents
IR photography useful in revealing contents of charred documents
Oblique lighting can also be used to contrast the writing vs charred background

13. Detection of charred document contents using oblique lighting

14. Digital image enhancement
Visual quality of digital picture is improved or enhanced
Digitizing- image is stored into memory by scanning an image with flatbed or digital camera and converting the image into digital intensity values called pixels (picture elements)
Image editors (Adobe photoshop) used to adjust contrast, color, etc.

15. Digital image enhancement using Adobe Photoshop screen and exclusion

16. Indented writings
Partially visible depressions appearing on a sheet of paper underneath the one on which the visible writing was done
Depressions due to application of pressure on the writing instrument and appear as a carbon copy of a sheet if carbon paper had been inserted
Like my check book