Police said the arrest followed a two-year investigation after officers were alerted that Rocks may have been in the country.
The information gathered by investigators indicated that he had been living an itinerant lifestyle to avoid detection and might be in Madrid, according to police.
Authorities said this led to a surveillance operation on a central street in the Spanish capital, during which Rocks, who was wearing a cap and sunglasses in an apparent attempt to partially conceal his face, was located and arrested.
Police said he gave different personal details during efforts to establish his identity and did not co-operate with officers.
They added that he was initially identified by his tattoos before fingerprint checks confirmed he was the man wanted by Police Scotland.
He later appeared before a court in Madrid and remains in custody pending a decision on his extradition to the UK.
Rick Jones, international director of the UK’s National Crime Agency (NCA), said: “This arrest marks the 101st arrest in Operation Captura, a multi-agency campaign aimed at tracking down the UK’s most wanted individuals in Spain.
“I pay tribute to the excellent work of our colleagues in the Spanish National Police who made this possible.
“Working with them, and other law enforcement partners, we are determined to do all we can to ensure fugitives are returned to face the courts.”
