Hi,
Has there been parallel legal investigatory actions on going by the French magistrates while the BEA is doing the technical investigation?
Yes ..
The "juge d'instruction" asked to "experts" called by him (in a pool of experts who are stdby for such investigations) to make their own investigations ..
It's the judicial process ... like in any accident (cars .. buses .. trains)
These experts will present their results at the trial
The BEA will also (certainly called by the judge) present their results
Note that the parties involved can have also their own experts and they will also present their results on the trial
These can be contradictory and it is the judge to decide (it can also call other experts for cons expertise)