Hi there,
It will always go to the Cps as they are responsible for ultimately making the decision whether to charge or not. However the initial process is that the Police have to believe there is enough evidence against the defendant to even pass the evidential test which is used.
If you would like more information please ask the Police officer in charge of your case or have a look here:
https://www.cps.gov.uk/victims_witnesses/resources/prosecution.html
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