* 13 bodies still unidentified
* Police expected to question driver on Friday
* Investigation focuses on speed, safety systems
By Tracy Rucinski
SANTIAGO DE COMPOSTELA, Spain, July 26 (Reuters) - The driver of a Spanish train that derailed, killing at least 80 people, was under police guard in hospital on Friday after the accident, which an official source said was caused by excessive speed.
The eight-carriage train came off the tracks, hit a wall and caught fire just outside the pilgrimage destination Santiago de Compostela in northwestern Spain on Wednesday night. It was one of Europe's worst rail disasters.
The source had knowledge of the official investigation into a crash which brought misery to Santiago on Thursday, the day when it should have celebrated one of Europe's biggest Christian festivals.
A judge in Santiago de Compostela, capital of the northern Spanish region of Galicia, was assigned to investigate the accident. The judge ordered police to question the train's driver, named as 52-year-old Francisco Jose Garzon.
It was not clear what kind of injuries the driver had suffered. He was not arrested, but he was under a police guard at the hospital and was expected to be questioned on Friday.
State train company Renfe said the driver was 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, the firm said.
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 to wait for definitive news.
With the festivities in Santiago cancelled on Thursday, hundreds of people went to the site of the wreck instead, where they watched cranes picking the mangled train carriages off the tracks.
"My brother-in-law lives close by and was helping pull out people, dead and alive, all night. He's very shaken. I've come now with some friends just to see how it all ends," said Manuel Garcia, one of the onlookers.
Video footage from a security camera showed the train, with 247 people on board, hurtling into a concrete wall at the side of the track as carriages jack-knifed and the engine overturned.
The train entered the bend at 190 km per hour (120 mph), according to local media reports. The speed limit on the curve was 80 km per hour (50 mph).
Investigators were trying to find out why the train was going so fast and why security devices to keep speed within permitted limits had not slowed it down.
The impact was so huge one carriage flew several metres into the air and landed on the other side of a concrete barrier. Bodies were strewn next to the tracks in the aftermath.
The dead included a U.S. citizen and a Mexican, and at least one British citizen was injured.
Train traffic resumed on Friday morning on the tracks parallel to the where the accident took place.
Spain's rail safety record is better than the European average, ranking 18th out of 27 countries in terms of railway deaths per kilometre travelled, the European Railway Agency said. There were 218 train accidents in Spain between 2008 and 2011, well below the EU average of 426 for the same period.
The disaster happened at 8:41 p.m. (1841 GMT) on the eve of a festival dedicated to St. James, one of Jesus's 12 disciples, whose remains are said to rest in Santiago's centuries-old cathedral.
The apostle's shrine is the destination of the famous El Camino de Santiago pilgrimage across the Pyrenees, which has been followed by Christians since the Middle Ages and has had a resurgence in popularity in recent decades.
Even though the festival was cancelled, pilgrims and tourists formed long lines to see the cathedral on Thursday.
"It's hard to make sense of a tragedy like this, especially on an occasion that is supposed to be joyous," said Jan Roser, a Catholic priest from Germany who had made the pilgrimage and was in Santiago for the festival.
Prime Minister Mariano Rajoy, a native of Galicia, visited the accident site and the main hospital on Thursday. He declared three days of official national mourning.
King Juan Carlos and Queen Sofia also visited the injured in hospital.
"All of Spain is united in grief with the bereaved families," the king said.