Meanwhile, the prosecutor of Vercelli has opened an investigation for manslaughter and aviatorio disaster.........
I don't have a knowledge of Italian law but it seems a bit unusual that a criminal investigation is opened before there is even any preliminary accident findings from civil aviation authorities.
I recall a somewhat similar situation in 1994 when F1 race driver Ayrton Senna was killed in a crash during the San Marino GP. A couple members of the Williams race team were charged with negligent manslaughter and tried in absentia by Italian prosecutors. It took several years to complete the legal process.
While it's tragic that the two test pilots lost their lives, a criminal case will likely take far longer to complete than a crash investigation by civil aviation authorities. So this could end up having a big effect on the AW609 certification efforts.