The very serious crashes take about 30 days. Instead of a typical crash report, this will be a full crash reconstruction. Every detail is analyzed. As the article mentions the event data recorders in both vehicles will be removed and analyzed. Also, the vehicle was most likely equipped with video recorders. The event data recorder and the video recording both will have the speed up to the impact. Another analysis will be on the amount of crush to each vehicle. The final reconstruction will tell prosecutors exactly what each vehicle was doing prior to and during the crash.