The 25-year-old was arrested on drug trafficking and burglary charges after he was found to be in possession of a large narcotics stash and stolen items including nine rifles, two machetes and a helicopter missile.
Police suspect the man stole the drugs and weapons from the home of a friend after he died when the car he was driving crashed into a ditch. Two others were also killed in the crash.
Several hours after that accident, officers were called to the home of the deceased driver to investigate a burglary.
After investigating possible criminal links between the suspect and the dead man, they arrested the 25-year-old seizing nearly half a kilogram of marijuana, as well as smaller amounts of crystal meth and the anaesthetic ketamine.
Along with the riles and machetes, they also found a revolver, twelve knives, three axes, three pocket knives, a baton and a laser pistol.
Police have now widened their investigation to look at other possible criminal activity carried out by the suspect, Spain's ABC newspaper reported.