@keep-it-real
It’s an easy and straightforward answer all round, irrespective of answering it in two parts because the answer is the same for both and that is a NO ...
Any case that is still under investigation, not withstanding the length of time elapsed since the initial crime was committed , will remain confidential and a subject access request under the FOI Act would not give up any information or details pertaining to it. This is to protect the integrity of the investigation and also because there may be detail(s) contained within the case files, even something which on first inspection, seems totally trivial and innocuous, but it could be that small detail that only the perpetrator would know/be aware of and therefore it’s important to maintain the cohesion and integrity of the file in the event that a perpetrator is arrested, arraigned and put before a Court of law and a subsequent Crown Court Trial ensues.
It’s probably not the answer that you were hoping for but I’m afraid that unless the perpetrator is identified, we will never know the details.
As an aside, if a perpetrator was identified and charged and went to trial at Crown Court, it may be the case that some investigative strategies and lines of enquiry undertaken, are so sensitive ( ie.may identify high risk under a scored Risk Assessment to a person/witness engaged within the investigation, may reveal Police investigation tactics , may identify a potential police informant ( CHIS - covert human intelligence source) etc), that even upon conviction and sentence, some details within the case files will NEVER be released and will be subject to PII ( Public Interest Immunity). I hope that helps and answers any further questions that you may have. Feel free to ask anytime and if I can answer it, I will. Take care and stay safe in these covid times .