A retired Argentinian naval officer has arrived in Spain to face trial for alleged genocide.
Ricardo Cavallo is accused of involvement in the torture and killing of thousands of people, including Spanish citizens, during Argentina's period of military rule in the 1970s and 1980s.
Cavallo was extradited from Mexico after what human rights campaigners say was a landmark court decision.
It is the first time anyone has been extradited from one country to another to stand trial for human rights crimes that happened in a third country.
