The driver of the high-speed train that derailed earlier this week just outside this northwestern Spanish city was released from the hospital Saturday and taken to a police station, where he is being held on suspicion of negligent homicide.
Interior Minister Jorge Fernandez Diaz made the announcement to the press in Santiago de Compostela.
The accident left 78 dead, three of whom have not yet been identified, the minister said.
Fernandez Diaz said the driver, Francisco Jose Garzon, would be taken before a judge before Sunday afternoon, when formal charges could be brought against him.
Garzon asserted his right to remain silent when police sought to question him at the hospital.
A total of 71 people, including 28 adults and three children listed in critical condition, are still hospitalized for treatment of injuries sustained the accident, officials said Saturday.
Authorities say excessive speed may be to blame for the crash, and Garzon apparently admitted earlier this week that he was going at around 190 kph (118 mph) on a curve with a speed limit of 80 kph (about 50 mph).
"I derailed, what am I going to do, what am I going to do," the 52-year-old Garzon, who has worked as a train operator since the 1990s, told the national government's representative in Galicia, where Santiago de Compostela is located.
The high-speed passenger train went off the tracks Wednesday along the route linking Madrid and the Atlantic coastal city of Ferrol.
The train involved in the accident entered service in 2012 and can go up to 250 kph (155 mph) on international rail networks and 220 kph (136 mph) on the Spanish high-speed rail system.
The signals on the stretch where the accident occurred were operating properly at the time of the derailment and the train had been inspected earlier in the day on Wednesday, Spanish railway operator Adif said. EFE