Schumacher had been skiing off-piste eight metres away from the designated ski-run, which prosecutors said was marked, when he had the accident.
Investigators are hoping to determine Schumacher's exact speed by analyzing footage from the camera mounted on his helmet frame by frame, lead prosecutor Patrick Quincy told a press conference on Wednesday morning.
Quincy said Schumacher was "an extremely good skier", but said one of his skis hit a rock which caused him to fall.
He could not give an estimate of how fast exactly the seven-time Formula One World Champion was going, but said the speed was going at an appropriate speed for a skier of his abilities.
Quincy said the investigation was "progressing well" and that police had heard from witnesses and doctors and examined the site of the accident.
He added the investigation would take several weeks.
Schumacher's skis were almost new and his bindings were in good condition, the press conference was told. The former Ferrari driver knew the piste well.
Quincy also said he was unaware of evidence to suggest Schumacher had left the piste to help a family friend as per news reports this week, stating that could not be confirmed from the video footage examined so far.