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Investigative interviewing, dissociative identity disorder and the role of the Registered Intermediary

Brendan M. O’Mahony (CJS Psychology, Diss, UK)
Becky Milne (COFI, ICJS, Portsmouth University, Portsmouth, UK.)
Kevin Smith (Major Crime Investigative Support, National Crime Agency, London, UK)

The Journal of Forensic Practice

ISSN: 2050-8794

Article publication date: 9 January 2018

Issue publication date: 23 January 2018




Intermediaries facilitate communication with many types of vulnerable witnesses during police investigative interviews. The purpose of this paper is to find out how intermediaries engage in their role in cases where the vulnerable witness presents with one type of vulnerability, namely, dissociative identity disorder (DID).


In phase 1, data were obtained from the National Crime Agency Witness Intermediary Team (WIT) to ascertain the demand for intermediaries in DID cases in England and Wales within a three-year period. In phase 2 of this study four intermediaries who had worked with witnesses with DID completed an in-depth questionnaire detailing their experience.


Referrals for DID are currently incorporated within the category of personality disorder in the WIT database. Ten definite DID referrals and a possible additional ten cases were identified within this three-year period. Registered Intermediary participants reported having limited experience and limited specific training in dealing with DID prior to becoming a Registered Intermediary. Furthermore, intermediaries reported the many difficulties that they experienced with DID cases in terms of how best to manage the emotional personalities that may present.


This is the first published study where intermediaries have shared their experiences about DID cases. It highlights the complexities of obtaining a coherent account from such individuals in investigative interviews.



The corresponding author is a Registered Intermediary. Author 3 is employed as an advisor to the Registered Intermediary service.


O’Mahony, B.M., Milne, B. and Smith, K. (2018), "Investigative interviewing, dissociative identity disorder and the role of the Registered Intermediary", The Journal of Forensic Practice, Vol. 20 No. 1, pp. 10-19.



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