At the Lab: Examining Questioned Documents
To begin this lesson, let's find out how good you are at noticing small details. Click on the image below to test what you know about the Canadian penny. Have fun!
Forensic Anti-Counterfeiting Specialist
- How did you do?
- Did you notice, for example, that the penny on the far right in the top row is missing the year?
- Or the penny second from the right in the middle row is missing the words 1 Cent?
- Did you spot the real penny?
- Documents such as paper currency, legal contracts, passports, and driver's licenses are also at risk.
- FACScomes into the picture:
- Can determine whether a document is authentic or if it is a forgery.
- Can determine who or what (i.e., what machine or type of machine) produced the document.
- Can even analyze handwriting samples.
Ink Analysis
•Look closely at this cheque. Do you notice anything suspicious about it?
- The number 6 and the word sixty don't look quite right - as if someone added them later. This cheque appears to have been forged, but how can we find out for sure?
- Use different methods to determine if this cheque is a forgery.
- An alternate light source (such as a laser or an incandescent bulb) over the cheque.
- If the cheque has been forged then different inks will be visible at different wavelengths of light.
- Another method Thin Layer Chromatography (TLC).
- Dips samples of ink and paper from the cheque into a solvent.
- The solvent interacts with the ink then migrates up the paper, creating bands of colour.
- If two ink samples from the cheque produce different bands of colour then the inks are different.
- This would suggest that someone forged the cheque by adding information with a different pen.
- TLC is very effective for spotting forgeries.
- Unfortunately it destroys the original sample.
Something to Try
- Find two washable black felt pens. Each pen needs to be a different brand to ensure the colour compositions are different.
- Cut a strip of paper towel or a coffee filter for each pen.
- Mark a black dot at the bottom of each strip.
- One at a time, dip the strips in water. Dip to just below the dot.
- Hold the strip and allow the water to soak up the strip.
- Watch what happens to the ink.
- Do you see the different bands of colour?
Determining the Source
- Examines the document under a microscope for identifying marks.
- Things like "scratches" on a photocopied document (caused by dirt or foreign material on the photocopier glass);
- Impressions in the document caused by a chip in a laser printer drum
- Damaged key on a typewriter.
- Next, attempts to find the machine with these same accidental characteristics.
- This will be the machine that produced the questioned document.
Handwriting Identification
- Called in to examine handwriting samples when there is doubt who the author is or when forgery is suspected.
- Will examine the questioned document carefully, looking for things such as:
- the slant of the letters, the spacing between letters and words, the size relationships between letters, angles, connecting and ending strokes of letters, distinctive letter formations, and the overall flow of the writing.
- the slant of the letters, the spacing between letters and words, the size relationships between letters, angles, connecting and ending strokes of letters, distinctive letter formations, and the overall flow of the writing.
- Will then compare the questioned document to a known standard (a sample from a known source) to see if they share common characteristics.
- If they do, that the same person wrote both documents.
- If they don't match then there is a probable forgery.
- A handwriting sample from a suspect can be requested or collected.
- If it is requested, then the suspect is asked to handwrite the exact wording found on the questioned document.
- A collected sample is a pre-existing piece of handwriting that is obtained from the suspect under police warrant, such as a grocery list, a letter, or a note.
Important Terminology
|
|
|