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Effective initial interview planning to undermine false claims of defence

Investigators effectively planned initial interviews to inform expert advice and undermine the defence of sexomnia in a case of rape and sexual assault.

First published

Key details

Purpose
Investigation cases
Topic
Rape and serious sexual offences
Investigation
Organisation
Contact

Detective Sergeant Michael Russell 

Start date

Description

A suspect claimed he had no memory of committing a rape and sexual assault offence and raised a defence of sexomnia at trial. Sexomnia is a sleep disorder characterised by an individual engaging in sexual acts while asleep. The suspect claimed that because of his sexomnia, he did not have mens rea (guilty mind) to commit the offences.

The suspect had initially denied any history of sleepwalking and had admitted to consuming five pints of alcohol on the night in question. He later exaggerated his history of sleepwalking in expert interviews.

Line of enquiry

Fortunately, officers had undertaken effective interview planning and asked important questions during initial interviews about sleep history, consultations with their general practitioner and the nature of the alleged acts. This early planning and interview strategy informed expert opinion and helped to challenge the suspect’s defence. 

The defence relied on expert evidence from two doctors, along with witness accounts from family and friends, describing a history of sleepwalking and unusual behaviour while asleep. The prosecution highlighted inconsistencies in the suspect’s accounts and expert testimony, particularly in relation to the impact of alcohol on sexomnia. Experts disagree on whether alcohol invalidates the diagnosis, with many asserting that alcohol-induced memory loss should not be confused with sleep disorders.

The acts committed were deliberate and complex, going beyond typical sleepwalking behaviour. The prosecution argued that these actions required conscious thought, undermining the automatism defence.

Outcome

The suspect was ultimately convicted of rape and sexual assault. 

Learning

If a suspect claims they have memory loss or suggest links to sleep-related disorders, it is important to ask about their sleep history, consultations with doctors, and the nature of the alleged acts, especially if the offence involves deliberate acts like clothing removal or changes in behaviour.

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