An investigation has been launched into how a high-speed Spanish train derailed killing 80 people near Santiago de Compostela on Wednesday.
One of the drivers, who Spanish media have named as 52-year-old Francisco Jose Garzon Amo, is due to be questioned on Friday.
The driver is not believed to have been arrested, but is under police guard in hospital. It was not clear what kind of injuries he had suffered.
Spanish newspapers have been reporting that Garzon Amo allegedly boasted on Facebook about driving a train at its speed limit of 200 kilometres per hour in 2012.
The Facebook page, now blocked, also purported to show a photo of the speedometer from the train posted by Garzon Amo.
State train company Renfe said the driver is a 30-year veteran of the firm with more than a decade of train driving experience. He had been driving trains on this line for about a year, Renfe said.
A judge in Santiago de Compostela, capital of the northern Spanish region of Galicia, has been assigned to investigate the accident.
The regional government said 95 people were still in hospital, 32 of them, including four children, in a serious condition. Medical experts were still trying to identify 13 of the bodies early on Friday, leaving distraught families waiting for definitive news.