Someone obtained my signature and thru a high resolution scanner managed to save a copy of my signature on his computer. He later put my signature on a fake document, and used a copy of the fake document in front of a court. The court accepted the copy of the fake document.
Question What forensic tests can be made to prove that my signature on the copy of the fake document was obtained from a scanner?
please note that I am more interested in an answer to my question than what to do in this case.
Match the "forged" document to the original from which the signature was scanned. Your signature is never the same twice. If they are identical, signature 2 is a copy.
How about looking at his computer to see if you can find the scanned signature?
- if it matches the one on the document, it could be where it came from
- if he has no reason to have a copy of your sig as an image, then he would need to explain why he has it.
If he used a copy of the fake document infront of court I presume he printed it. If it was high quality it was likely printed on a colour printer. These leave traces on the document, details
The EFF has some additional info
Maybe they transferred the file from the computer to print else where or even emailed it. Checking if any Lnk files point to files on a recently attached pendrive might help. What about traces of web mail, where by he sent the attachment to themselves or someone else?
Ronan
BitHead I don’t have the original. He has it.
4n6art Most probably he didn’t use his computer.
Ronanmagee Most probably he used a laser printer for printing the scanned signature.
Guys Thank you for your contributions, but as I said earlier, I am really interested in getting a technical answer to my question. That is what forensic evidence can one get to prove that a signature was scanned prior to printing having only a photocopy of the questioned document?
I am confused, you say that he didn't use a computer in your reply and yet your original post says that he did. You say used a laser printer and a scanner, how could he do this without a computer. You need to clear things up otherwise you likely won't find any help.
To be honest your up the creek without a paddle. If you don't have access to the original documents.
I would get your solicitor to ask for the original documents and then have a handwriting specialist compare the forged signature with the original signature. They can give you the probability of having two signatures exactly the same in every detail.
If he did use a computer for any part of this process then the signature analysis will give you enough legal footing to ask for the forensic analysis of his computer.
There will be <almost> nothing you can do with a single photocopied document as the quality is degraded and much of the original evidence has been lost.
what forensic evidence can one get to prove that a signature was scanned prior to printing having only a photocopy of the questioned document?
If you only have a photocopy then this is extremely hard. One approach would be to look for tool marks, that is, if the scanner had any marks on the surface prior to scanning these would be carried through to the printed document (if the scanned doc was not cleaned up). Please remember that the photocopier may also have introduced tool marks on your copy so these would need to be eliminated by taking a base mark copy from the photocopier.
As DFICSI says, without the original your pretty much outa luck. If you can get the original then you should be able to see the indentation of pen as you leaned on page. This will generally leave groove in the paper, where as if it was scanned the surface would be flat or uniform throughout due to the nature of the printer burning the data onto the page (if its a laser printer). You would need a hand writing specialist to put some weight behind this.
I don't know any other 'technical' way to prove from an original let alone a photocopy that this document has been forged.
Please keep us informed with your chosen way forward.
Ronan
You don't need a computer forensics expert for this. This issue is actually more commonplace than one would think. Many idiots think they are the first to do this, but they aren't. Therefore there are many ways to deal with this. You dont necessarilly need any expert, just the testimony and weighing the credibility of the people involved.
Nonethless, since you asked,
A handwriting expert will suffice. They have many ways of knowing originals from copies.
In addition, or in the alternative, you can get someone with an ink background to test the "ink".
All that being said, even if it gets into evidence, so what? A judge or jury accepting it as "credible" is an entirely different issue and is looked at in context of the facts.
If, God forbid, you are looking for a way to correct your method, don't do it. You'll get caught.
I am not quite sure what is the issue, here, since it should be easy to examine the document and prove that the signature was written using a different ink/pen, etc., from the rest of the content. He/she did present this as an original document, right?
If not, but they are arguing that the evidence presented to the court is an authentic reproduction (or, are you saying that that they say that you digitally signed it), then find a forensics firm that has good image analysis capabilities and get the court to agree to allow that document to be analyzed.
No matter what the resolution of the scanner, it is not that difficult to demonstrate that what was produced was the the product of a printer/photocopier (which should exclude the document from consideration, anyway), but even so, no matter how the image of your signature was pasted onto the document, image analysis should be able to detect it.
A handwriting expert may be helpful but I would argue that your case lies in proving that the document is not and cannot be an original, and the fact that he/she cannot produce an original is grounds to exclude the document as evidence (this, of course, depends upon the rules governing evidence in your locality). Barring that, I believe that you could create reasonable uncertainty that the document was not altered, enough to exclude it from being considered as evidence.
The same goes for proving that the image was scanned. Handwriting is an analog process. Scanning is digital. In the conversion of the analog to the digital format, you are going to have some details lost (the edge of the ink as it blurs into the paper), as well as added (defects, etc., in the paper that was scanned). These can be compared to a document that you can demonstrate that you did sign to produce sufficient doubt as to the authenticity of the other document to exclude it.
If I may, reading the original question might help.
From what OP says
a signature has been scanned
then it has been printed or plotted over a document
than a copy (photocopy) of this document has been produced to Court
the Court accepted this copy
I doubt that the last photocopying will mantain enough details on the copy produced to Court to ascertain that the signature was faked on the original.
So, nothing "technical" or "handwriting expert" can help in this case, simply the Lawyer should represent to the Court that his client does not recognize the produced copy as a document signed by himself and challenge the opponent to produce the original (on which experts can have their saying).
jaclaz