First wings folded makes a nice summation
Here
The two cents I would like to add is that the remit of the public prosecutor is to conduct a criminal investigation concerning an aircraft accident, period. He is to determine if a criminal act has been committed that caused the accident, he is not tasked with determining any other possible causes such as may be related to spontaneous equipment / software failures or deficiencies which may have caused the accident -that falls under the provenance of the BEA. Thus M. Robin is only looking for evidence of a crime. If he discovers enough the evidence to reasonably conclude that a crime has likely been committed then he will report such; he tells he has and he did. While there may be other possible reasons for this accident such as an unrecoverable equipment or software failure either due to the nature of that failure or due to pilot error in response due to inexperience it is not M. Robin's issue to address, that is BEA's issue. To sum up M. Robin was tasked to determine if enough evidence existed to indicate that a crime had likely been committed, he believes he has done so.