The Spanish Civil Guard has released images showing its canine unit specialists searching inside trains at the Adamuz train accident site.
They are attempting to gather evidence to identify the victims.
The death toll from a collision between two high-speed trains has risen to 42 after another body was found in the wreckage, regional authorities said Tuesday.
Last Sunday, an Iryo train travelling from Málaga to Madrid derailed at 19:40 local time with 317 passengers on board.
It invaded the adjacent track, which was being used by another train carrying around 184 passengers which had departed from Madrid and was heading to Huelva.
