The US state of Florida has executed a Cuban man for murdering a policeman in 1978.
The Supreme Court rejected a petition for stay of execution for 61-year-old Manuel Valle.
Relatives of the victim said they felt relief that justice had been done after 33 years.
Spain had pleaded for the execution not to go ahead on humanitarian grounds.
Just a week ago the state of Georgia executed Troy Davis for murdering a policeman. He went to his death proclaiming his innocence.