Hmm, my concerns are that future incidents you will not get full disclosure for worry of prosecution and that can then lead to more fatalities as the root cause may not be discovered.
One also questions the polices expertise in all of this, surely it is the role of the AAIB to take the evidence and then use their knowledge and expertise to sort out the relevant information from the chafe to arrive at the correct conclusion.
The police in requesting the information will be presented with it all without the skill set to differentiate from what is relevant to the case and what is not and the people they would then have to approach to accurately disseminate the relevant evidence would be the errrrrrr AAIB.