A train driver suspected of causing Spain's worst train disaster for decades is facing charges of "homicide with impunity", effectively meaning manslaughter.
Investigators are looking into possible failings by 52-year-old Francisco Jose Garzon Amo after the Madrid to Ferrol service derailed on Wednesday night as it approached the city of Santiago de Compostela.
Early this morning, he left hospital after receiving treatment for chest trauma and head injuries.
Mr Garzon Amo has been taken to a police station, but has so far refused to answer officers' questions and is expected to be interrogated by a judge.
He must appear before a judge before 7.40pm local time (6.40pm Irish time) tomorrow to comply with Spanish law.
Visiting Santiago, Interior Minister Jorge Fernandez Diaz said that he believes there are "rational indicators of the train driver's liability".
"He has been detained since 7.40pm on Thursday for the alleged crime of reckless homicide," Mr Fernandez Diaz said.
He said the driver had once again declined to make a statement to police this morning.
Meanwhile, a news conference was told this afternoon that passengers on the train will be able to pick up their belongings today.
They are being held at a school near the scene of the accident.
Medical staff in Santiago de Compostela have identified the last three remaining bodies using DNA tests.
A public funeral for the 78 dead would be held at Santiago cathedral on Monday.
30 people are still believed to be in a critical condition in hospital.
In addition to people from all over Spain, nationals from the United States, Mexico and Algeria are believed to be among the dead.
Authorities are in possession of the train's so-called "black box", which is expected to shed further light on the cause of the disaster.
It has yet to be examined by investigators, as protocol demands that the police investigation is concluded first.
Adif, Spain's railway agency, confirmed that a high-tech automatic braking programme was installed on the track for most of the journey but stops just 5km south of where the crash occurred.
From that point on the driver has sole control of the brakes.
"Regardless of the system in place, the drivers know the speed limits. If these are respected, an accident should not take place," a spokeswoman said.
Early indications suggested the train was travelling at around 190km/hr - more than twice the 80km/hr speed limit - when it crashed while heading into a curve.
Gonzalo Ferre, president of Adif, said the driver should have started slowing the train 4km before reaching a dangerous bend that train drivers had been told to respect.
"Four kilometres before the accident happened he already had warnings that he had to begin slowing his speed, because as soon as he exits the tunnel he needs to be travelling at 80 kilometres per hour," Mr Ferre said.