In The Art of Racing in the Rain by Garth Stein, what was controversial about Ayrton Senna's last race?

The controversy regarding Ayrton Senna's last race lay in the differing accounts of how he died.

Accordingly, Ayrton Senna had died when his car veered off the course on the day of the San Marino Grand Prix. He had been traveling at one-hundred-and-ninety-miles per hour, and his car had crashed into a concrete barrier. Ayrton died after sustaining injuries to his head when a piece of suspension penetrated his helmet. His death was controversial, however, because there was no consensus as to how he died. The question lay in whether Ayrton died en route to the hospital or whether he died on the tracks.

Yet, camera footage of the accident had "mysteriously disappeared," leaving no conceivable way of determining the true cause of Ayrton's death. To add to the controversy, the FIA (Federation Internationale de L'Automobile) was known to have a high stake in the affair. According to the law in Italy, a driver's death on the tracks had to be investigated immediately, and all races were to be discontinued until investigations were complete. On the other hand, if the driver died in the helicopter on the way to the hospital, the race was allowed to continue. Since any moratorium always led to the loss of millions of dollars in revenue for the FIA, sponsors, and stakeholders, it was clearly in the FIA's interest to assure the continuation of the race.

So, the controversy lay in whether there was any attempt on the part of the FIA to cover up the true cause of Ayrton's death.