He had driven trains past the spot of the accident 60 times during his time with Renfe, company president Julio Gomez-Pomar told private television Antena 3.
Some media reports described Garzon Amo as a speed freak who once posted a picture on his Facebook page of a train speedometer at 200 kph.
A caption read: “I am on the edge, I can’t go faster or else I will be fined.” The page has since been taken down.
But Garzon Amo also has his defenders.
“He is an excellent professional,” said Antonio Rodriguez, who joined Renfe alongside Garzon in 1982. “It is the first accident he has ever had.”
Renfe said the train a model able to adapt between high speed and normal tracks had no technical problems and had just passed an inspection on the morning of the accident.
But experts have raised questions about the track’s speed signalling system.
Since high-speed trains use the route, it has been equipped with an automatic speed control system known as the European Rail Traffic Management System, under which a train’s brakes can be automatically applied if speeding.
But the secretary general of Spain’s train drivers’ union, Juan Jesus Garcia Fraile, told public radio that the system was not in place at the crash site.
Many of the passengers were said to be on their way to a festival in honour of Saint James, the apostle who gave his name to Santiago de Compostela.
The city’s cathedral will host a memorial service on Monday for the victims of the crash.