* 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) - Thedriver of a Spanish train that derailed, killing at least 80people, was under police guard in hospital on Friday after theaccident, which an official source said was caused by excessivespeed.
The eight-carriage train came off the tracks, hit a wall andcaught fire just outside the pilgrimage destination Santiago deCompostela in northwestern Spain on Wednesday night. It was oneof Europe's worst rail disasters.
The source had knowledge of the official investigation intoa crash which brought misery to Santiago on Thursday, the daywhen it should have celebrated one of Europe's biggest Christianfestivals.
A judge in Santiago de Compostela, capital of the northernSpanish region of Galicia, was assigned to investigate theaccident. The judge ordered police to question the train'sdriver, named as 52-year-old Francisco Jose Garzon.
It was not clear what kind of injuries the driver hadsuffered. He was not arrested, but he was under a police guardat the hospital and was expected to be questioned on Friday.
State train company Renfe said the driver was a 30-yearveteran of the firm with more than a decade of train drivingexperience. He had been driving trains on this line for about ayear, the firm said.
The regional government said 95 people were still inhospital, 32 of them, including four children, in a seriouscondition. Medical experts were still trying to identify 13 ofthe bodies early on Friday, leaving distraught families to waitfor definitive news.
With the festivities in Santiago cancelled on Thursday,hundreds of people went to the site of the wreck instead, wherethey watched cranes picking the mangled train carriages off thetracks.
"My brother-in-law lives close by and was helping pull outpeople, dead and alive, all night. He's very shaken. I've comenow with some friends just to see how it all ends," said ManuelGarcia, one of the onlookers.
Video footage from a security camera showed the train, with247 people on board, hurtling into a concrete wall at the sideof 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 curvewas 80 km per hour (50 mph).
Investigators were trying to find out why the train wasgoing so fast and why security devices to keep speed withinpermitted limits had not slowed it down.
The impact was so huge one carriage flew several metres intothe 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 leastone British citizen was injured.
Train traffic resumed on Friday morning on the tracksparallel to the where the accident took place.
Spain's rail safety record is better than the Europeanaverage, ranking 18th out of 27 countries in terms of railwaydeaths per kilometre travelled, the European Railway Agencysaid. There were 218 train accidents in Spain between 2008 and2011, well below the EU average of 426 for the same period.
The disaster happened at 8:41 p.m. (1841 GMT) on the eve ofa festival dedicated to St. James, one of Jesus's 12 disciples,whose remains are said to rest in Santiago's centuries-oldcathedral.
The apostle's shrine is the destination of the famous ElCamino de Santiago pilgrimage across the Pyrenees, which hasbeen followed by Christians since the Middle Ages and has had aresurgence in popularity in recent decades.
Even though the festival was cancelled, pilgrims andtourists formed long lines to see the cathedral on Thursday.
"It's hard to make sense of a tragedy like this, especiallyon an occasion that is supposed to be joyous," said Jan Roser, aCatholic priest from Germany who had made the pilgrimage and wasin Santiago for the festival.
Prime Minister Mariano Rajoy, a native of Galicia, visitedthe accident site and the main hospital on Thursday. He declaredthree days of official national mourning.
King Juan Carlos and Queen Sofia also visited the injured inhospital.
"All of Spain is united in grief with the bereaved families,"the king said.