A French prosecutor says he wants to get hold of an alleged mobile-phone video of a skiing accident that critically injured Formula One legend Michael Schumacher.

Schumacher’s fall at the Meribel ski resort in the French Alps eight days ago, in which he hit his head on a rock, has left the 45-year-old in a medically-induced coma for a severe brain trauma.

Questions have emerged about the circumstances of the accident, and Schumacher’s manager, Sabine Kehm, announced on Saturday that his family has given French authorities a camera affixed to his helmet to help elucidate the case.

Albertville state prosecutor Patrick Quincy told The Associated Press that French investigators are also taking steps to obtain a copy of a smartphone video cited in a report by German news magazine Der Spiegel.

Quincy declined to comment further before he holds a planned news conference this week.

Spiegel reported late on Saturday that an unnamed man had contacted the magazine claiming to have captured the accident on video while filming his girlfriend on his smartphone just a few metres away.

The unnamed witness, described only as a 35-year-old flight attendant from the western German city of Essen, claimed Schumacher had been skiing gently between two ski pistes at no more than 20kmh before his fall.

The magazine didn’t show the video on its website, nor claim that its reporters had seen it.

Spiegel said the witness told them he planned to hand the video to prosecutors.

Also on Sunday, Schumacher’s brother Ralf and father Rolf returned to the Grenoble hospital where he has been receiving care.

Schumacher is the most successful F1 driver in history, racking up a record 91 race wins.

He retired from Formula One in 2012 after garnering an unmatched seven world titles.