More tributes have been paid to the teacher who died when a coach carrying schoolchildren home from a ski trip crashed in northern France.
The driver, named in reports as Derek Thompson, 47, appeared before a judge in Chalons-en-Champagne, prosecutor Christian de Rocquigny confirmed. He has now been released and is returning to England on condition he will return to a French court at a later date.
Most of the 49 British nationals who were on the coach are back in the UK, however seven people remain in hospital in France, the Foreign Office said.
Initial tests had showed Mr Thompson was not under the influence of alcohol or drugs, and local police are believed to be investigating whether he might have fallen asleep at the wheel.
After a court hearing, Mr de Rocquigny said the driver, who was slightly injured, was being investigated for involuntary homicide and involuntary wounding.
"He is going back to England on the condition that he will return to a French court later," he said. "Witnesses who were driving in the area near the coach saw the vehicle repeatedly swerve towards the verge.
"The tachograph indicates some unexplained variations in speed in the nine minutes before the accident, the judge explained. While being questioned the driver, having denied falling asleep, has acknowledged that it was possible that he did so."
Dozens of children were injured when the bus flipped over and plunged to the bottom of a motorway embankment in the Champagne-Ardenne region.
Teacher Peter Rippington, 59, died in the crash near Rheims, and his wife Sharon and daughter Amy were also injured in the crash, which involved 29 pupils from Alvechurch Middle School in Alvechurch, Worcestershire. A 13-year-old girl was critically injured, Mr de Rocquigny said, and was transferred to the Necker children's hospital in Paris, where he said her condition was unknown.
Tributes poured in for Mr Rippington, who was described by Bryan Maybee, chairman of governors of Alvechurch Middle School, as a "dedicated and inspirational teacher" who would be sadly missed by all those who knew him.