HIGH PROFILE and MONEY
There are two factors here that will ensure finding a 'responsibility trail '.When substantial amounts of money are concerned there will be parties that require that 'someone pays' and the legal 'chasers' will then get to deal with it in their own way.
Eventually someone will be held financially responsible which may THEN lead to a further legal battle with the relevant authorities.
With few actual witnesses or corroborated information then the process will be protracted and complicated.
As alluded before this could well be the equivalent of a 'Shoreham Showdown' for non scheduled quasi commercial operations, and ramifications for many operations including genuine clubs.
The CAA have as part of their mandate a responsibility to ensure safe passage for commercial passengers both scheduled and 'charter' but it is unreasonable to expect them to police the entire aviation spectrum with current resources, and with the latitude now being shown via EASA regs prosecutions are frequently only possible with substantial intelligence led information, and or input from other parties.
I hope this does not reduce the level of 'cause investigation' with regard to the recent loss of two UK pilots in Spain, because there may well be some useful lessons to be learnt from that.