In the UK it is the CPS who bring a criminal prosecution to Court. The police conduct the investigation. The CPS is independent of the police.
The principles for liaison between the CPS and the AIB are set out in a Memorandum of Understanding dated October 2008, between these two parties.
Here is a link to the full document:
https://www.cps.gov.uk/legal/assets/...2030.10.08.pdf
I would suggest that the section setting out the Basic Principles of
Co- operation are worthy of note.
Reference to this document may assist the forum in discussing and debating the issue. You may in particular note that the superior interest remains public safety, this takes precedence over criminal investigation. However the AIB may consider a criminal prosecution agency as an interested party and avail a report of its findings to such an agency.
A revised MoU is expected to be published in the near future. Perhaps it will deal more specifically with the thorny issue of CVR evidence.