Investigative services

Credibility Assessment

The Centre for Forensic Neuroscience was established in 2002, with our main offices in Glasgow and Liverpool, provides polygraph testing services (often referred to as lie detection) and credibility assessment internationally.

We have the UK’s largest team of dedicated expert examiners, with Dr Keith Ashcroft as the Principal Forensic Polygraph Examiner. Each are established professionals in their own discipline, and are available for instruction in your location throughout the United Kingdom, Europe, the Middle East and the rest of the world. We take instructions from Corporations, Government Agencies and Private Individuals. 

We are members in good standing at the National Polygraph Association (USA), the American Association of Police Polygraphists, director member of the  UK Polygraph Associationthe Society for Psychophysiological Researchas well as the American Polygraph Association. We have been trained at American Polygraph accredited & British Accreditation Council academies, including advanced training at the Behavioural Measures UK Polygraph Training Centre operated by Behavioral Measures, as well as the Peak Credibility Assessment Center, and also members of the Society of Forensic Interviewers; we are therefore conversant with best practice.  As such we are independent, impartial and objective in our professional work.

We specialise in providing specific issue examinations using only accepted protocols and standards in accordance with the American Polygraph Association and ASTM International (committee E52 on Forensic Psychophysiology). We employ strict quality control procedures, as well as using two examiners to confirm results. Our state-of-the art computerised polygraph systems, such as the Limestone Paragon Acquisition System, have a High Resolution 24 bit Analog to Digital Conversion for superior recording and analysis capability.


For resolving relationship difficulties, including financial investigations between intimate partners. Please note that the opinions of such examinations are based on the interpretation of the physiological data and are therefore investigatory in nature; the conclusions, should not be used as singular evidence in civil or criminal proceedings.


Victim and alleged perpetrator testing in those having legal representation only. Please note that the opinions of such examinations are based on the interpretation of the physiological data and are therefore investigatory in nature, and other supporting evidence should be taken into account before any actions are taken. In cases where polygraph examinations are not feasible we can employ a Visual Assessment of Sexual Preference.


In legal terms, a child is defined as anyone under the age of 18. Therefore, safeguarding children is about protecting all those under 18 from harm. This can be done by investigating individuals with access to children, either in an employment context, or within an intimate or family relationship. 


Polygraph testing for private sector employees who are under investigation for allegations relating to economic loss to their employers.


Prevention, detection and investigations of insider attacks.


Polygraph used within a therapeutic setting to assist in disclosure, sobriety and relapses in sex addiction; as well as treatment resistance etc.. We receive referrals from various therapists who offer proven psycho-educational programmes for the treatment of sex and pornography addiction and support programmes for partners. Please note that we cannot be instructed in cases where the partner views a polygraph interview and examination as the only way of regaining trust (there must be additional sources). In addition, there must not be any evidence of punitive/vindictive motives as opposed to therapeutic considerations for seeking a therapeutic polygraph.


We provide polygraph screening testing for Public and Private sector companies, as well as periodic honesty testing, including drug screening. Our services include psychometric testing using the Holden Applicant Screening Measure. The Holden Applicant Reliability Measure was developed by Dr. Ronald Holden at Queen’s University and has been further researched by Dr. Angela Book at Brock University. This dynamic psychometric instrument provides valuable insights on employment candidates in an effort to save resources related to recruitment and training.

PAIRED TESTING (Marin Protocol)

Used in situations where one of two opposing witnesses is most likely being deceptive. Effectively used in mediation contexts.


For identifying concealed assets.


Polygraph testing for those who have been granted leave to Appeal (N.B. ~ in the UK this cannot form the basis of appeal against conviction) (Pro Bono).


Polygraph testing for those alleging acts of misconduct or accused of same.


Polygraph testing of individuals seeking asylum are used to determine the validity of the claims of the petitioner in immigration cases. The statements of the petitioner requesting asylum can be verified by a polygraph test. The results of the test can assist in making an informed decision with regard to granting or withholding asylum.


Forensic / Criminal matters: such as homicide, sexual violence, theft, fraud, sabotage, and espionage. Allegations of sexual abuse are subject to our enhanced service with two forensic polygraph examiners. CFN provides solicitors and lawyers with an assessment as to the credibility of the defendant and witness in criminal matters.


To effectively manage sex offenders in the community.


Polygraph testing to assess the value of critical intelligence sources.


Polygraph testing for sports legal matters.





How to Schedule a Polygraph Interview & Examination:

  • You can schedule a polygraph interview and examination by using our contact form, or by calling us directly on: 07790732828 to speak directly with an examiner, so we can provide an in-depth description of the process, fees, advice, and guidance for the examinee in readiness for polygraph testing.
  • When requested, we can have a polygraph examiner conduct the interview and polygraph examination at a office in your location to satisfy the required optimal testing environment; therefore our fees reflect this best practice level of service.
  • In accordance with the American Polygraph Association recommendations, and good practice, we do not conduct tests in a home environment.
  • Please note our fees are dependent upon the gravity of the issue to be investigated and the distance from our test centres.
  • A retainer fee is normally required to secure the appointment. We use SquareUp for all financial transactions and billing.
  • The results/opinion is given within the polygraph interview/examination process. 
  • A written report will be given on request.
  • In forensic cases a second examiner will peer review all of the data and analyses.
MUST HAPPEN ON voluntary basis
It is vitally important to stress that all examinations must be taken on a voluntary basis. No person should be intimidated or coerced into taking such an examination. If you have been threatened to participate in a polygraph interview and examination, then this could have a negative influence over the whole testing process. As a strict policy we do not accept instructions where we believe coercion or threats are present.
Fees vary on the type of exam and where it will be conducted. Credibility assessment requires extensive training, continuing professional development, as well as specialised instrumentation, therefore our fees reflect this fact. Our examiners are also qualified as Expert Witnesses. A retainer fee is required on instruction. 
Various U.S. Government research studies have found that the single-issue (one question) credibility assessments, conducted by an appropriately qualified examiner, are 87 to 95 percent accurate.  It is undeniably the most accurate method for determining truth or deception. Notably the accuracy of multi-question formats is approximately 80 percent due to a number of confounding memory related factors. 
neutral testing environment
Usually we can arrange a suitable neutral testing environment in your particular location to ensure that tests can be conducted in a proper manner. For therapeutic services, our consultants use clinic settings, should this be a necessary requirement.
Failing a polygraph examination
It is vitally important to stress that before any life-changing decisions are made on the basis of a ‘failed’ polygraph examination there must be other corroborating evidence to substantiate the case. 
it takes 2 hours or more
Please also note that the whole process takes around two hours or more to complete.
single issues question formats
You will be advised that we strongly recommend only single issues question formats as this has been proved scientifically to be the most accurate method to employ. Thus for example:

R1   Did you take the money from the First bank in Mosley Street, Manchester last Thursday?

R2   Did you take the money from the First bank located in Mosley Street, Manchester last Thursday?

R3   Did you take the money that First bank in Mosley Street, Manchester on Thursday last week?

Furthermore, the answer to each question is limited to either ‘yes’ or ‘no’. Ideal questions must be: Concise, be clearly understandable to the examinee, not be presumptive of guilt, not test for hypothetical intentions, or, about future behaviours, nor state of mind, or ask for an opinion, and lastly legalisms, as well as medical/diagnostic terms, should be avoided. In addition, one should never test for more than one issue per relevant question, and address primary details, rather than teritary facts. 

The primary relevant questions must specify the action or behaviour as closely as the recalled mental image of the issue being investigated.  

Any additional issue must be done with a separate polygraph test. Examinees will be sent information on how to prepare for the test and be evaluated for suitability according to various criteria; such as for example:

  • Be free of any serious illness.
  • The examinee should not have been subjected to any accusatory interviews prior to the examination.
  • The examinee must not be under the influence of alcohol or substances of abuse at the time of the test.
  • The examinee must have had a reasonable amount of sleep prior to the test.
  • The examinee must be sufficiently hydrated and had something to eat prior to the test.
It should be noted that there are certain limitations of polygraph testing:

      • The test results relate to what the examinee perceives.
      • Not everyone is suitable for testing due to individual physiological and psychological differences and states.
      • The clarity of issues being tested.
      • Number of issues being tested.
Our examiners work in conjunction with specially trained interpreters to provide polygraph tests in most languages. They are also trained in cross-cultural sensitivities in order to engage more effectively with people from different cultures.
Please note the our examiners do not re-test the work of other examiners as a matter of company policy and professional ethics.
In most cases the results are given during the examination process, or, soon thereafter if a peer review is necessary. Our examiners will at all times ensure complete confidentiality and discretion. 
The examinee must provide government identification (Photo ID Card, Passport, Driving License ) on arrival for verification purposes.
How many Questions can be asked?
Given the ubiquity of television programmes showing so-called ‘Lie Detector Tests’ it is expected that the polygraph examiner can ask multiple questions on various issues; this is simply not possible in scientific terms.  In formal, valid credibility assessment, only one issue is address within the examination to ensure accuracy. You cannot mix issues within the same polygraph interview and examination.
How does the polygraph instrument work?
The underlying theory of how the polygraph instrument identifies the particular arousal pattern for each channel does not rely on fight, freeze or flight i.e. threat of punishment, consequences of being caught lying or even psychological set. Nor is it a conditioned response, or related to anxiety (there is no basis in research for this). These notions are outdated and irrelevant to modern polygraph science. Current understanding refers to what is known as the ‘orienting response’ to novel or important stimuli, which are intrinsically related to experiences in autobiographical memory, emotional salience and the act of lying requiring increased cognitive processing. Specifically, it takes more cognitive activity to lie than to tell the truth because you need to construct a narrative, so the degree of cognitive processing can be relevant in determining deception. This collection of underlying neural processes give rise to increased autonomic arousal that is routinely detected by the polygraph instrument. Thus, essentially, we are analyzing the strength of attention as determined by autonomic arousal.
How much does it cost - fees?
Our fees depend on the complexity of the investigation and the disbursements for travel and serviced offices, where necessary. 

Limestone Technologies Inc

We have a long association with Limestone Technologies Incorporated and the Centre for Forensic Neuroscience Limited is an authorised reseller. Contact us for expert advice, sales and after service.