This did get a bit off topic, didn't it.
In any case, I've had a reply back from the FIU:
"Thank you for your email. The investigation into the circumstances is complete and a report has been submitted to the PF. This is in keeping with standard procedure involving all incidents resulting in a fatality. Lothian and Borders Police cannot comment further on the likelihood of charges or otherwise as the PF will make this decision.
I trust this information is of use,"
So in other words, who knows!
I find the comment on charging curious. Surely the police charge and the PF decides whether or not there is enough evidence to prosecute, or is my understanding completely cock-eyed?