Spanish authorities are investigating the driver of the train that crashed in north-west Spain killing 80 passengers in the country's worst rail disaster for 70 years.
Investigators are looking into possible failings by the driver after the Madrid to Ferrol service derailed on Wednesday night as it approached the city of Santiago de Compostela.
A second probe launched into the catastrophe will look at the train's in-built speed regulation systems. Early indications suggest the train reached 118mph - more than twice the 50mph speed limit - when it crashed while heading into a curve.
The train's driver, named in local reports as Francisco Jose Garzon Amo, is expected to be interviewed by an investigating judge in possession of the train's "black box" data recorder. He is not believed to be under arrest at this stage.
One Briton has been confirmed by the Foreign Office to be among 168 injured passengers, while the regional government in Galicia said it had so far only been able to confirm the identities of 67 bodies. The authorities are still working to identify the other 13 and DNA tests are expected to be carried out on those with catastrophic injuries.
A US woman killed in the wreck has been named by Catholic Church officials in America as Ana Maria Cordoba, an employee of a diocese near Washington DC. Her husband and daughter were injured as the family travelled to visit her son who had completed a pilgrimage to Santiago de Compostela, the Catholic News Service reported.
Meanwhile, more than 30 people including four children remain in a critical condition, according to reports. Visiting the hospital in Santiago where most of the wounded are being treated, King Juan Carlos said: "All I can say is that all Spaniards are united in this moment and we are with the victims, with the families and with the friends of the victims."
Mr Garzon Amo is a 30-year employee of Renfe who is believed to have taken control of the train from a second driver about 65 miles south of Santiago de Compostela. According to reports, one of the drivers made a desperate call to Renfe ahead of the bend, saying: "I'm going at 190kmh, I'm going to derail."
In a second call to Renfe after the accident, the driver explained that he was trapped in the train. He is reported to have said: "We are human, we are human. I hope there are no dead because they would fall on my conscience."
The full horror of the disaster was revealed in harrowing video footage of the moment the high-speed train derailed. Posted on YouTube, the security camera footage shows the middle carriages of the Class 730 train smash into a wall before the engine crashes on to its side.