The driver of the train that derailed in north-western Spain, killing 78 people, is now being detained by police on suspicion of negligent homicide, Minister of Interior Jorge Fernandez Diaz announced Saturday, according to CBS News.
Previously, Francisco Jose Garzon, 52, had been held on suspicion of recklessness.
Garzon was released from the hospital Saturday after having suffered minor injuries, but remained in police custody, according to Reuters.
He is reportedly refusing to respond to police questioning.
Garzon has until Sunday evening local time to make a statement if he chooses. On Sunday evening, a judge will decide whether to press formal charges against him, CNN reported.
More than 140 were hurt, 36 seriously, after all eight carriages of the Madrid to Ferrol train came off the tracks near Santiago de Compostela.
Spanish police on Friday slightly lowered the death toll from 80 and said they had identified 75 of the fatalities.
Prime Minister Mariano Rajoy has announced that two investigations are being carried out — one judicial, the other by the investigative commission for rail accidents, under the Ministry of Public Works — the BBC reported.
The investigations appeared to be focusing on the culpability of Garzon, a driver with 13 years experience.
The Guardian cited the Spanish daily El Pais as reporting that he had received an order to reduce speed just seconds before the crash, and had acknowledged it by pressing a button in the driver's cab.
Despite that, he was either unwilling or unable to apply the brakes on the train, which was running five minutes behind schedule.
El Pais quoted Garzon as telling railway officials by radio while still trapped in his cab that the train had been travelling at 120 miles per hour.
He allegedly said:
"I was going at 190 [kilometers per hour]! I hope no one died because it will weigh on my conscience."
Australia's ABC cited the head of the Galician police service Jaime Iglesias as saying that Garzon, who was formally detained by police on Friday morning, was accused of criminal recklessness.
A Spanish judge had ordered police to question him following reports he was going more than twice the 80 kilometres per hour speed limit when the train derailed on a sharp bend and slammed into a concrete wall just outside the pilgrimage city of Santiago de Compostela a day earlier.
However, Iglesias said:
"The driver has refused to answer the police authorities."
The case would now "proceed to a judicial process as soon as possible."