Francisco José Garzón Amo was in custody at the hospital where he is recovering from minor injuries sustained during the accident that claimed the lives of at least 80 people.
In screengrabs from Garzón's alleged Facebook page (since taken offline), the 52-year-old can be seen bragging about pushing his high-speed train to the limit underneath photos of a speedometer reading 200 km/h (124 mph).
"Woah you are going so fast, braaaaaaake," one of Garzón's friends wrote in response to the photo posted last year. "If I went any faster, they’d fine me," Garzón responds.
He later added, "what fun it would be to drive side-by-side the police and then pass them by, triggering the speed radar. Haha, bit of a fine for [train operator] Renfe, ha ha!"
Authorities in Spain are still trying to determine what caused the accident, but believe the train was traveling at over twice the speed limit when it his a curve and derailed.
Immediately before the crash, Garzón radioed in to say the train was "doing 190" km/h (120 mph).
Shortly after he was quoted as saying "We're only human! We're only human! "I hope there are no dead, because this will fall on my conscience."
Garzón, a 30-year vet of Spain’s national rail network, had been running the Madrid-Ferrol route for over a year.
[screengrabs via Facebook, Twitter]