The Spanish Civil Guard has released images showing canine unit experts searching the train at the scene of the Adams train crash.
They are trying to gather evidence to identify the victim.
More bodies have been discovered in the wreckage of two high-speed trains, raising the death toll to 42, local authorities said Tuesday.
Last Sunday, at 19:40 local time, an Italian train bound for Madrid from Malaga derailed with 317 passengers on board.
It entered an adjacent track used by another train carrying around 184 passengers, which had departed from Madrid and was headed for Huelva.