Forensic Analysis and Investigations


None of the factors that produce handwriting are rigid and unchanging. In addition to the organic factors (physical anatomy and health, mental acuity, etc.) there are environmental factors affecting handwriting. These include the writing instrument itself, the writing surface and what lies beneath it, and other variables of the writing situation.  Handwriting can also be affected by factors such as injury, illness, medication, drug or alcohol use, stress, the writing surface, the writing instrument, or attempted disguise.  Because the primary motor pattern is itself a fluid image and because there are so many organic and environmental variables that interact in the production of handwriting, it has become an accepted axiom that a person is unlikely to ever duplicate any signature exactly. Each person has a unique range of natural variation that forms a distinctive code.

  1. The examination of signatures comprises of size measurements, form, direction, slant, pressure, speed, line quality, physiognomy, alignment, starting and ending strokes, and diacritics etc.
  2. Fluent or rapid motion is impossible in a copied signature, whatever type of forgery is applied. Its tempo would always be slower than the genuine one.  The same applies to disguised writing, as well as to writing that is being imitated.  Laboured writing means uncertainty.  This is seen in trembling and interrupted strokes (pen-lifts).   
  3. A person’s signature, because of both its frequency of use and the nature of its application, tends to become more individual than any other combination of letters that he writes


Established in 1966, the American Polygraph Association (APA) is the world's leading association dedicated to the use of evidence-based scientific methods for credibility assessment. The APA promotes the highest standards of professional, ethical and scientific practices for its 2700+ members through the establishment and publication of standards for professional practice including techniques, instrumentation, analysis, research, training and continuing education.

Examination on Psychotic Patients:

Research data indicate polygraph examinations are useful in the evaluation of patients with severe psychiatric illnesses.  A variety of psychological and physiological processes, including some that can be consciously controlled, might affect polygraph examination results.  It was generally accepted that schizophrenia patients have a reduced physiological response to various stimuli.  The use of medications and movement disorders including tardive dyskinesia reduce the validity of the test, however no substantial systematic research was performed to validate the extent of the effects.  Current research suggests increased sympathetic tone and increased skin conduction with exacerbation of the mental states.  The authors hypothesized that examination of psychotic patients will demonstrate that patients will generally regard psychotic content as the truth, and beyond the boundaries of their psychotic content, the polygraph will detect truths and non-truths as in all other individuals.

Polygraph Examinations at the CCMA:

Polygraph Examiners are accepted as Expert Witnesses whose evidence needs to be tested for reliability.  The duty of the Commissioner is to determine the admissibility and reliability of the evidence. Polygraph tests may not be interpreted as implying guilt but may be regarded as an aggravating factor especially where there is other evidence of misconduct.  It is accepted in our courts that the result of a polygraph is evidence in corroboration of the employer’s evidence and can be taken into account as a factor in assessing the credibility of a witness and in assessing the probabilities.


From a judicial viewpoint, evidence may be defined as "all relevant information that, if admissible in court, is presented".  Evidence is given verbally by witnesses who appear viva voce and in writing by means of such documents that are admissible.  It is further complemented by beliefs, judicial notice and admissions.  It all forms the proof from which a conclusion must be reached.

All information is not evidence.  Information refers to knowledge that has been observed, heard and experienced and which could be of assistance to the crime investigator.  This information can directly or indirectly assist in the reconstruction of a crime scene, tracing of suspects, recover of missing property or to identify witnesses.  Evidence, on the other hand, is valid information, which if admissible in court, strives to prove facts or issues.

Evidence and the furnishing of proof stand apart from each other but are related to each other within the total judicial process.  Evidence includes individual facts that are presented in court for consideration.  On the other hand, proof refers to the sum total of all the facts presented during evidence.  Evidence is therefore the basis for, and medium whereby, proof is furnished.

Criminal Liability:

Probably the most important principle of criminal liability is captured in the “dictum actus not facit reum nisi mens sit rea”, or "an act is not unlawful unless there is a guilty mind".  To establish criminal liability, the State must prove, beyond a reasonable doubt, that the accused has committed:

  1. Voluntary conduct which is unlawful “actus reus”, accompanied by
  2. Criminal capacity, and
  3. Fault “mens rea”, in the form of intention or negligence.

A trial court will normally begin its judgement by considering whether the State has proved the “actus reus”, before going on to consider the other two elements of liability.

The conduct must:

  1. Be carried out by a human being,
  2. Be voluntary, and
  3. Take the form:
    1. Of a commission or omission,
    2. Of a state of affairs prohibited by law, or
    3. Of causing a consequence prohibited by law.

Type of Examinations:

  1. Forensic Criminal Specific (specific criminal matters)
  2. Periodical screening
  3. Pre-Employment
  4. Special cases

Test Type:

  1. Airforce MGQT as per APA regulations


  1. Lafayette LX400
  2. Measures five (05) physiological channels

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