Self-Forgery of Signatures

What if the signer was the writer himself, disguising the stroke?

Forensic routine is well acquainted with forgery by imitation: someone copies another person's gesture. There is, however, the opposite movement, and it accounts for a significant share of the signatures disputed in court. The holder signs, deliberately distorts his own stroke and, months later, denies the act alleging forgery. This is self-forgery, also called a disguised signature or disguise by self-falsification.

The calculation behind it is simple: whoever distorts his own signature knows it will not match the exemplars, and counts on a hasty expert report confirming the formal divergence. An examination conducted with method takes another route and frequently reaches the opposite conclusion.

That is why the examination does not stop at the shape. A signature invented on the spot, with no habit behind it, comes out different at every attempt. A signature fixed by habit repeats, under any disguise, a set of elements the writer does not control, and it is on that set that the comparison rests.

Above, two signatures invented on the spot, with no resemblance to each other; below, four natural signatures by the same person, with a stable line — Above, two "signatures" invented on the spot by the same person: the graphic features do not repeat from one to the other. Below, four natural signatures by that same person, with the stable line that habit has fixed.
Figure: Anna Koziczak, *Intentional Handwriting Modifications* (Forensic Sci Add Res, 2023) · CC BY 4.0

Forgery by imitation

Slow stroke, produced under the watch of the eye
Command tremors and undue stops along the path
Retouching and reinforcement to correct the design
Uniform pressure, without the natural axis of the writer's hand
Form sometimes convincing, dynamics always poor

Self-forgery

Fast, fluent stroke: the writer's hand is the usual one
Initial attacks and terminal strokes preserved by automatism
Graphic minima unchanged, because they escape control
Alteration concentrated in what is visible: size, slant, flourishes
Different form, identical genesis

The principle that underpins the examination

The graphic gesture is commanded by the brain, not by the hand

It is Solange Pellat's lesson that structures the distinction: habitual writing is not modified at a single stroke, and the writer who tries to distort it alters the form without reaching the genesis. Elements of a general order, visible to any reader, change. Those of a genetic order, invisible to the lay reader and to the writer himself, remain.

What more than twelve thousand signatures revealed about people who distort their own

The intuition described above is no longer merely bench experience. Research published in the Archives of Forensic Medicine and Criminology examined more than twelve thousand signatures collected from two hundred people, who were tasked with deliberately altering their own handwriting so as not to be recognised as its authors, without the alteration looking artificial. For the final assessment the researchers selected precisely each participant's most successful attempts, the ones that would present an examiner with the greatest degree of difficulty.

The result confirms a stable pattern of behaviour. Whoever distorts his own signature concentrates the effort on what catches the eye, on the so-called pictorial effect of the mark, and leaves untouched the features he does not notice or whose very existence he does not suspect. It is in that asymmetry that the examination finds its answer.

Two legible signatures by the same person: one self-forged and one natural, with the overall shape altered and the underlying features preserved — Self-forgery in a legible signature: the overall shape changes, but the set of features beyond the writer's control stays in place, and it is that set which sustains the comparison.
Anna Koziczak, *Signatures as an object of autoforgery (self-forgery)*, Archives of Forensic Medicine and Criminology, vol. 73, no. 3, pp. 257-271, 2023.

What writers alter most

84%Structure of the characters in the opening part of the signature

57%Structure of the characters in the middle part

51%Structure of the characters in the final part

46%Size of the signature

43%Legibility

39%Impulse of the gesture

34%Writing speed

32%Axial slant

What they almost never alter

1%Presence or absence of additions and complements

2%Manner of execution of the signature

4%Arrangement of the characters in relation to one another

5%Shape of the signature line

7%Placement of the signature in relation to the baseline

8%Direction and tendency of the baseline

8%Spacing between the elements

A documented case

What changed and what stayed, in a real self-forgery

The same study describes, signature by signature, what one writer managed to alter in his own legible signature and what stayed the same without him noticing. It is the asymmetry in its purest form.

What the writer altered

the structure of the first letter of the surname and of letters in its middle part
the size of the signature
readability, which came out higher than usual
impulse, which came out lower
the height of above-line components, lowered against the mid-line

What stayed, without him noticing

the structure and connections in the final part of the surname
the space between the surname and the first-name initial
the number of components and the order in which they are drawn
the degree and characteristic manner of shortening the first name
the additions, such as the absence of a dot after the initial

A case of autoforgery in a legible signature described by Anna Koziczak, Signatures as an object of autoforgery (Archives of Forensic Medicine and Criminology, vol. 73, no. 3, 2023).

The diagnostic inversion

The inverted signal is what distinguishes the two frauds

In self-forgery, the divergences appear in the foreground features while agreement is maintained in the secondary ones: the more individualising those preserved features are, the more their persistence between the questioned signature and the exemplar points to the writer's own hand, even though the general form has changed. In forgery by imitation the picture is exactly the opposite: the forger copies what is visible and goes wrong precisely in the secondary features. Reading a disputed signature by similarity of form alone is looking at the wrong side of the evidence.

Source: KOZICZAK, A. Signatures as an object of autoforgery (self-forgery). Archives of Forensic Medicine and Criminology, v. 73, n. 3, p. 257-271, 2023. DOI 10.4467/16891716AMSIK.23.021.19321.

Denying one's own signature has consequences

Once the authenticity of a private document is challenged, it ceases to be trusted until its truthfulness is proven (CPC, art. 428, I, Brazilian Code of Civil Procedure), and the burden of that proof falls on the party that produced the document (CPC, art. 429, II). This is why the challenge is used as a strategy: it shifts the cost and the risk of the forensic examination to the other party.

When the examination shows that the disputed signature came from the very hand of the person who denied it, the strategy turns against its author. Altering the truth of the facts amounts to litigation in bad faith (CPC, art. 80, II), with the penalties of CPC, art. 81, and the episode taints the credibility of everything else that party has claimed in the proceedings.

On the other side, for someone accused of forgery, the same examination is the most effective defence: showing that the stroke came from the holder's own hand removes the need for witness testimony to dispel the accusation.

CPC, art. 428, IA challenged private document ceases to be trusted until its truthfulness is proven

CPC, art. 429, IIOnce authenticity is challenged, the burden of proof lies with the party that produced the document

CPC, art. 80, IIAltering the truth of the facts amounts to litigation in bad faith

CPC, art. 81Fine and compensation to the party harmed by the bad-faith conduct

ExemplarsThe examination requires contemporaneous exemplars of unquestionable origin, taken before the dispute whenever possible

What if the signer was the writer himself, disguising the stroke?

The graphic gesture is commanded by the brain, not by the hand

What more than twelve thousand signatures revealed about people who distort their own

What changed and what stayed, in a real self-forgery

The inverted signal is what distinguishes the two frauds

Denying one's own signature has consequences

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