this is JMO but obviously they must be working on the basis of hypothesis that the motive was sexual. They will want to be doing something with the IE offences and try them in the same proceedings. I can see that being the first area of legal argument because his defence I think would argue the offences should be dealt with separately. If they find evidence of sexual assault I believe they would arrest, charge and indict and I imagine make an application if necessary (even if that’s a formality) to have the offence heard at the same proceedings as the kidnap and murder. I don’t think they’d “let it go” on the basis of the murder charge as it’s not in the public interest, I think it will be seen as an aggravating factor and will have ongoing implications on any conviction about sentencing, later assessments about whether the accused remains a danger to society and treatment during prison sentence as a sex offender. JMO.
In short, I think it would depend on the evidence available as the CPS must believe there’s a realistic prospect of a conviction to make the decision to charge and if there’s no evidence at all then they would not be able to make that decision in good faith. I think likely however in those circumstances they’d put forward the hypothesis that the motive was sexual even if there was no evidence to charge with a sexual offence. IMO It would definitely be a thorny issue which might explain the level of search activity so that they can proceed with a charge of a sexual offence in connection with kidnap and murder. MOO