Caputo stood on the other side of the desk, his arm thrust forward, holding up three fingers.

'We are working on three main theories at the moment/ Zen replied evenly. 'The first is that the perpetrator…'

He glanced at Caputo, who was waddling bow-legged around the room with his hands clutched like claws beside his hips.

'… was a cowboy/ concluded Zen.

'AwhatT Caputo shook his head furiously. Zen covered the mouthpiece of the phone.

'An AmericanV hissed Caputo.

'… that he was an American/ Zen told the Questore.

'But the United States naval authorities have explicitly denied that he was one of their men!'

'Exactly!' retorted Zen. 'According to this theory, the suspect was an undercover CIA agent who had been entrusted with the mission of murdering one of the Greek sailors, the son of an influential Communist politician.'

He looked triumphantly at Caputo, who gave him an enthusiastic thumbs up.

'And the second theory?' pursued the Questore after a pause which suggested that he was taking notes.

'The second…'

Caputo had transformed himself into a smaller, slighter, quicker individual moving around the room with exaggerated naturalness, glancing furtively from side to side, his hands occasionally darting out to one side or the other as though of their own accord.

'… is that the man was a common pickpocket/ Zen went on, 'who had infiltrated himself into the port area disguised as an American sailor. He approached the Greek sailors, intending to make a touch, and when they started roughing him up under the mistaken impression that he actually was an American, he reverted to type and pulled a knife.' "I don't like that one so much/ the Questore replied neutrally. 'Reflects badly on the city. What about the third theory?'