(CNN) -- Investigators are studying the camera that was on former world champion driver Michael Schumacher's ski helmet for clues to the cause of a skiing accident that left him critically injured in a French hospital.
French media reports late Friday suggested police had seized the camera from Schumacher's family. It's not yet clear whether it was filming at the time of the accident.
But his manager, Sabine Kehm, said in a statement Saturday that the family had handed the helmet camera over to the authorities voluntarily.
"That this should have been done against the wishes of the family is untrue," she said.
Kehm said Schumacher's condition remains critical but stable.
His doctors say no further update on his condition is expected before Monday, Kehm said.
Schumacher suffered severe head trauma in the accident last Sunday in Meribel, in the French Alps. He is in a medically induced coma and has undergone two operations.
Kehm said Tuesday that friends and family who were skiing with him say he hit a rock hidden under deep snow and was catapulted head first onto another rock. He was not moving fast at the time, she said.
Friday was the former Formula 1 champion's 45th birthday, marked with a silent vigil by fans who gathered outside the hospital in the city of Grenoble where he is being treated.
Schumacher, the most successful driver in Formula 1 history, won 72 Grand Prix races between 1996 and 2006 for Ferrari. The automaker posted a message on its website Friday.
"This is a special day for Ferrari and all its fans, as it is Michael Schumacher's birthday," it said. "At the moment, he is tackling the most important fight of his life and therefore we want to send him very special wishes."
CNN's Phillip Taylor and Saskya Vandoorne contributed to this report.