Brazilian police say an officer who was having an affair with a Greek diplomat's wife has admitted his "cowardly" murder. Investigators said Kyriakos Amiridis is thought to have been stabbed to death by 29-year-old police officer Sergio Moreira at the behest of the diplomat's Brazilian wife, Francoise Amiridis. Moreira told police he was romantically involved with 40-year-old Mrs Amiridis and that they planned the killing together.