Investigative interviewing

Faso Aishath Updated by Faso Aishath

  • Every effort must be made to identify possible witnesses. Failure to do so may compromise the investigation. 
  • It is important to document the steps taken to identify and contact possible witnesses.  
  • Face-to-face interviews are generally the most effective approach for gathering evidence. 
  • Other options for interviewing people and gathering information include video-based and telephone calls, instant messaging or email interviews, group interviews and surveys. 


Interviewing people to uncover information relevant to the issues under investigation is a key part of credible research. During this phase of the investigation, it is vital that the NHRI makes every reasonable effort to identify possible witnesses.   

If the effort is inadequate, the investigation could rightly be criticised. It is also possible that new witnesses come forward and provide evidence that contradicts the findings of the NHRI.  

NHRI investigators should recognise that interviewing can be a very sensitive and difficult process. This is especially true when interviewing people in vulnerable situations – for example, victims of sexual or gender-based violence or people deprived of their liberty1 – and people who are vulnerable because of their age, disability, sexual orientation or gender identity or another characteristic.  

The first rule of interviewing is to ‘do no harm’. NHRIs have a responsibility to protect, as well as to investigate. The last thing an investigator wants to do is to add further trauma. Therefore, consideration should be given to who interviews, where the interview is held and whether the interviewee requires a support person. 



Witnesses who may be crucial to an investigation might not always come forward. It is therefore the responsibility of the NHRI to identify potential witnesses and reach out to them.  

Canvassing for potential witnesses can be done in different ways, including through social media, posting notices at a scene, going door-to-door in a particular area and posting a questionnaire on the NHRI website, among others. 

If the NHRI is investigating issues related to an event, the following questions can help identify possible witnesses: 

  • Who was there at the time? 
  • Who may have been there? 
  • Who should have been there? 
  • Who was there immediately before or after the event? 



There can be hundreds of possible witnesses to an event. In a situation like this, an investigator needs to ‘triage’; that is, they must use their judgment to decide who must be interviewed and who it is not essential to interview. 

In answering this question, an investigator needs to consider a range of factors, such as: 

  • Seriousness of the investigation and the resources available  
  • Time constraints set out in the investigation plan  
  • Proximity of the witness to the event/issue 
  • Potential uniqueness of the person’s evidence 
  • Availability of the person to be interviewed  
  • Any concern regarding the person’s credibility or identity 
  • Ensuring that the voices of those most affected are given appropriate prominence. 



Face-to-face interviews are the most effective way to gather information and evidence relevant to an investigation. Wherever possible, investigators should seek to conduct face-to-face-interviews with key witnesses. 

The main advantages of face-to-face interviews are that: 

  • Questions and answers are free-flowing and in real time 
  • New issues that come up can be addressed immediately 
  • The investigator is better able to keep control of the process 
  • The identity of the interviewee is more likely to be assured 
  • The investigator is better able to assess the credibility of the interviewee  
  • The investigator can view and record any physical evidence produced by the interviewee, such as video records or photographs 
  • It can be more difficult for an interviewee to be evasive or deceptive. 

A well-structured interview can also help build rapport between the investigator and the interviewee, particularly if thought has been put into selecting the best interviewer for the circumstances and for the interviewee. 

A commitment to conducting face-to-face interviews demonstrates the professionalism and thoroughness of the investigation by the NHRI. There are, however, issues that may affect whether a face-to-face interview can be conducted, such as availability, geography, cost, access and lack of cooperation. 



Skype and FaceTime interviews are an efficient method for conducting interviews, although they lack some of the advantages that come from being in a room with the interviewee. The main benefit of this approach is to eliminate the time spent travelling and associated expenses.  



Telephone interviews have similar advantages to Skype and FaceTime interviews. They are ideal for low-level fact-finding and are convenient where people have access to a phone.  

There are, however, some issues an investigator needs to keep in mind. For example, the identity of the interviewee may be uncertain and the interviewee may have other people present who influence what they say. In addition, the interviewee may try to record the interview, which can impact the integrity of the investigation. 



Interviewing a witness in real time by email or an instant messaging service, like WhatsApp, can be useful. The method is cheap, quick and produces a copy of the interview that can be attributed to the person’s e-mail or messaging account. It does, however, have all the disadvantages of telephone interviews. Further, some people may not have access to a computer or smartphone. 



Surveys and questionnaires are useful when investigating systematic issues that impact hundreds of people. They allow the NHRI to collect large amounts of raw data on set themes and questions. 

Group interviews are another effective way to collect information and perspectives on an issue. They are an efficient use of the NHRI’s time and resources, however, there can be disadvantages if there is conflicting opinion within the group.  



Chapters 6-8, Undertaking Effective Investigations: A Guide for National Human Rights Institutions (APF, revised 2018) 

Chapter 5, Preventing Torture: An Operational Manual for National Human Rights Institutions (APF, APT, OHCHR, 2010) 



How did we do?

Planning an investigation

Setting up the interview