Mexican prosecutors have filed manslaughter charges against the driver of a monster truck that ran out of control into a crowd of spectators, killing nine.
Chihuahua state prosecutors said Francisco Velazquez Samaniego did not meet age and health requirements to drive the truck in the exhibition.
The 51-year-old appeared before a judge as another person died in hospital, raising the death toll from Saturday's accident to nine. At least 80 people were hurt.
Velazquez Samaniego said in court that his helmet came off as the truck bounced over old cars and he lost consciousness when his head hit metal bars inside the cabin.
Organisers of the event in Chihuahua have said hundreds of people gathered without permission in the pit area of a makeshift arena in a park.
The pit area was unprotected by a barrier, feet from where the monster truck known as Big Show was crushing a pair of old cars, leaping into the air and rolling over their hoods and roofs. Video of the accident shows the truck coming down hard off the second car, bouncing and then speeding out of control into the crowd.
One organiser said the spectators had not been moved out of the pit zone before the show because "crowd management is very difficult".
Motor-sports experts, however, pointed at the organisers, saying the set-up of the state-sponsored show was deficient and life-threatening.
The safety situation was "about as bad as it could get", said Marty Garza, spokesman for the Monster Truck Racing Association, the primary safety organisation for the industry in the United States.
"There was some pretty blatant disregard for the safety of spectators. There is no excuse for why the spectators were situated as they were, period."
Velazquez Samaniego, 51, appeared before a judge wearing a neck brace .
"I was driving to one side and then I turned around and drove to the other side, my helmet came off and I hit my head and lost consciousness," he said. "I wasn't conscious when the truck fell."