On 25/01/2018 11:33, Martin Brown wrote:
Have a look for yellow dots using visible blue lights

https://en.wikipedia.org/wiki/Printer_steganography

http://seeingyellow.com/

Includes links to websites which can help you decode the dots

Your are right. That is by far the easiest non-destructive test.

A 10x loupe easily sees the printer forensic yellow dots in good light.
They are all but invisible under a 3x loupe without using blue light.

I have had the documents passed now, however, regarding the yellow dots
I tested this with blue light and a 10x loupe and none had them. This
printed documents from 3 seperate sources.

Having said that
my copies are on an old laser B&W only
Other copy done at PO and most likely B&W only printer
And the other was from the sheriffs office possibly just B&W printer
also. I suspect the yellow dots only applies to colour laser printers.