SANTIAGO DE COMPOSTELA, Spain — The train driver did little to hide his taste for speed. He posted a photograph of a locomotive speedometer needle stuck at 200 kilometers, or about 125 miles, per hour on Facebook last year, boasting that the reading “has not been tampered with” and openly relishing the idea of racing past the authorities.

“Imagine what a rush it would be traveling alongside the Civil Guard, and passing them so that their speed traps go off,” he wrote, in all capitals. “Hehe, that would be quite a fine for Renfe, hehe,” referring to his employer, the Spanish rail company.

Now that train driver, Francisco José Garzón Amo, a veteran with more than three decades of experience, is under investigation by a judge in connection with one of Europe’s worst rail accidents in recent years.

In a chilling video from a security camera, the passenger train he was driving rounded a curve at high speed on Wednesday night, tumbling violently off the track, slamming against a curved wall and piling up in a twisted wreck. Eighty people were killed.

On Thursday, Spanish news media reported that the driver had said the train’s speed had been about 120 miles per hour, more than double the limit in the stretch of track where the train derailed. On the day of the wreck, he took over from another driver just 60 miles before the crash, according to Spanish news reports.

The train was almost full, carrying more than 200 passengers and merrymakers returning to the region for a special holiday on Thursday. July 25 is the feast day for St. James the Apostle, the patron saint of Spain, who for centuries has inspired pilgrims to walk El Camino de Santiago, or the Way of St. James. The pilgrimage has had a burst of popularity in recent years, drawing walkers from around the world.

After the crash, the city of Santiago de Compostela canceled its extensive celebration and the authorities urged people to donate blood. Thousands made a very different kind of pilgrimage to the site of the disaster, watching as rescuers used cranes and trucks to hoist the engines of the wrecked train. All — children, teenagers and older people — stood in funereal silence.

Nearby, in a building where an information center had been set up, police officers kept the victims’ families from the public eye. Some walked around the building in tears, hugging and comforting one another, while others grew frustrated waiting to see their loved ones.

“Now, at 9:30 p.m., is when they allowed us to go and see our family member,” said María, a relative of a victim who did not want her full name used. “Twenty-four hours waiting, in these conditions. That’s too much.”

Most high-speed lines that are part of the European rail traffic system are covered by a GPS-based surveillance network that constantly monitors trains’ speed and automatically brakes them at speed limits.