My understanding is that there's a push that means when people are allowed o change their birth certificates they will always have been the acquired sex, IYSWIM. So, even tho' the murder took places so long ago, the reporting has to be based on current identity.
There's some controversy over how this might be implemented with respect to, e.g., the Soham murders if this should come to pass. Will the crime stats be retrospectively updated (I don't think so but it's all very murky).