Michael Schumacher ski helmet camera 'examined'
Investigators in France are examining a camera which had been fixed to the ski helmet of injured Formula 1 driver Michael Schumacher, media reports say.
Authorities were hoping the device may reveal clues about the circumstances of his skiing accident in the French Alps, a source told the AFP news agency.
Police also interviewed Schumacher's teenage son, who witnessed the crash.
Fans earlier held a vigil outside the French hospital treating the F1 legend, to mark his 45th birthday.
Ferrari supporters gathered at the clinic in the city of Grenoble and held a one-minute silence on Friday afternoon.
Schumacher's family said in a statement they had been moved to tears and "utterly overwhelmed" by the "incredible sympathies" shown by the fans.
The German champion, who retired in 2012, is in a medically induced coma after suffering head injuries during a fall in the resort of Meribel last Sunday.
His helmet cracked on impact when he hit a rock while skiing off-piste.
He remains in a stable but critical condition after two operations to remove blood and pressure from his brain.
Doctors confirmed on Tuesday that Schumacher had shown signs of improvement, but was still "not out of danger".
They ruled out giving a prognosis for his condition in the coming days and months.
But it is medically possible for someone to spend several weeks in an induced coma and make a full recovery.
'Fight of his life'
News of the camera's existence emerged late on Friday afternoon.
AFP said Schumacher's family had handed both the device and helmet to the authorities for investigation.
It remains unclear whether the camera was switched on at the time of the accident.
The news comes after members of Ferrari clubs in France and Italy travelled to Grenoble to mark the birthday of the most successful driver in Formula 1 history.
Ferrari - the racing team with which Schumacher had 72 of his 91 F1 wins - said in a statement that it wanted to send him very special wishes for his birthday as he tackled "the most important fight of his life".
Spokesman Renato Bisignani said people had been encouraged to dress in red and bring flags, as "a sign of closeness to Michael Schumacher, done in a very respectful way".
Michael Schumacher retired from F1 for a second time in 2012.
He won seven world championships and secured 91 race victories during his 19-year career.
The driver won two titles with Benetton, in 1994 and 1995, before switching to Ferrari in 1996 and going on to win five straight titles from 2000.
He retired in 2006 but made a comeback in F1 with Mercedes in 2010.
After three seasons which yielded just one podium finish, he quit the sport at the end of last year.