The body of the 51-year-old man was discovered outside Malaga airport on Friday morning.
An airport worker alerted police after finding the body bound to a bench.
Police said the man, who had been stripped from the waist down and had his hands tied behind his back, could have been sexually assaulted.
It is not immediately clear whether the man was waiting for a flight, had recently flown to Malaga or was in the area for another reason.
Semi-naked British man found dead outside Malaga airport - BBC News