Frequently Asked Questions

about the signature verification process.

When a signature on a document appears strange or inauthentic, there are specific steps to follow to determine whether it is genuine or not:

Signature verification is a comparative process

In order for a forensic document examiner to provide an opinion on whether a signature is genuine or not, the disputed signature is compared to numerous known, genuine signatures of the person who was supposed, or purported, to have signed the document.

Other terms used to refer to genuine signatures include: ‘exemplars’, ‘standards’, ‘known’ or ‘admitted’ signatures.

The most important rule guiding the comparative process is COMPARE LIKE TO LIKE.

In order to provide known signatures that meet this rule, please bear in mind that people have different styles of signatures for different types of occasions:

  • Formal (contracts, wills, important documents)
  • Informal (personal correspondence, routine business matters, cheques)
  • Careless (signatures written in a hurry such as receipts, dockets, requisition slips, all types of official forms etc.)
  • Initials that appear on contracts next to certain paragraphs, at the bottom of pages, and also on similar documents to careless signatures.

In the light of this, if the disputed signature is a formal one, on a last will and testament or on a contract, then formal signatures must be provided for comparison, and so on down the list – try to provide exactly the same style of signatures or initials on the same type of document for comparison.

Conversely, it would not be appropriate to compare a formal signature with a careless scribble.

If a disputed or known signature is written in the space provided on a form, it will be more squeezed in appearance than if more space was available for the person to write in their normal style. Thus, signatures on forms are often unnatural and do not make good comparison material, unless the disputed signature was also written on a form.

Because people’s handwriting changes over time, the second rule of comparison is that the known signatures must be relatively CONTEMPORANEOUS. This means that the known signatures must have been written between one or three years before or after the disputed one (preferably before). Very often it is a struggle to obtain contemporaneous known signatures, especially in cases of disputed wills. In such cases, the absence of contemporaneous signatures is mentioned in the forensic report.

The third rule for admissibility of known signatures is that they must be VERIFIABLE. Therefore, it is preferable if they are on official documents or cheques. Signatures written on a plain piece of paper (especially of a deceased person) would not be regarded as verifiable. For ideas on where to obtain known signatures, please see sources.

The handwriting on original documents enables an assessment of the pressure characteristics and the line quality of both the disputed and the known signatures.

Written strokes that are tremulous, written very slowly or with unnatural pen lifts and hesitation are regarded as having poor line quality.

The examination is done microscopically. If photocopies, scans or faxes are the only format that can be provided, these can be examined, but a lot of the above-mentioned information is lost. In this event, a disclaimer is included in the forensic report stating that photocopies or scans were used.

Between five and fifteen known signatures is ideal. For a stronger level of opinion to support your case, provide as many known signatures as possible.

If the known signatures vary considerably from one another, more exemplars are required than would be the case if the signatures are consistent.

Even though the questioned signature is often the most important element in a forensic investigation, it is preferable to submit the entire document for examination. Isolated pages or electronic extracts of the questioned signatures would not be sufficient.

The document examiner can often find evidence that is initially not suspected, in the form of sets of initials or strange marks on the document. Additional physical evidence such as staple holes, differences in font and layout, erasures and tip-ex can also be significant.

Human beings are not robots and therefore do not write their signatures in an identical manner each and every time. Examples of natural variation include letters of different size, shape and slant, a t bar that is placed high sometimes and low down at other times, full stops and underscores that are present on some signatures but absent on others and so on.

Natural variation among a set of signatures is indicative of genuineness. If the signatures within a set are identical to each other, questions arise as to whether they are traced or digitally placed upon a document (electronic cut ‘n paste).

Forensic document examiners first establish the pattern of natural variation among the set of known signatures, and examine the disputed signature to see whether it fits this pattern, or contains anomalies that fall outside the pattern.

These are signatures or samples of handwriting that are written in the presence of an investigator or forensic document examiner. They are genuine signatures that can be compared with the questioned material.

This means that the selection of known signatures could be determined by what the client wants to prove. For example, he or she could select only those signatures that look similar to the disputed one, or those that do not, depending on the desired outcome of the examination process.

A forensic document examiner never takes anything at face value. It is not unknown for writers to deliberately distort their own signatures so as to be able to withdraw from the terms of the contract at a later stage.

A disputed signature may look strange because the writer was under the influence of medication, alcohol or other mind-altering substances at the time of writing.

There are many other influences on handwriting including stress, illness, shock, utilising an unusual writing instrument, an awkward writing position, problems with eyesight and injury to the arm or hand among many others.

Over and above the red flags for forgery, the writer’s subtle habits are as important, if not more so, than obvious features such as a flourished capital letter, a line underneath the signature or the size or slant of the letters. The examiner looks for evidence of many unconscious writing habits which together contribute to cumulative evidence.

Background information about the writer of the known signatures is helpful:

  • Age
  • Gender
  • Country in which writing skills were learned
  • Left- or right-handed
  • Eyesight
  • Standard of education
  • Economic status
  • Injury to hand or arm
  • Health
  • Prescription medication
  • Addictions