Once he seemed reassured and a little more relaxed, Fry produced the broken crucifix in its clear plastic evidence bag.

‘Do you recognize this, sir?’

‘Nadezda had one just like it,’ said Halak. ‘But it wasn’t broken like that.’

‘Would there be any way to tell whether it was hers?’

‘My sister – she always put her initials on her things, in case someone tried to take them from her. She would scrape it, you know.’ He mimicked using a small, sharp object like a needle on the back of his hand.

‘She scratched her initials on her possessions?’

‘Yes.’

Fry picked up the bag and turned it over. She held it up to the light and squinted at the back of the crucifix. The metal was flaking away and discoloured. But in the middle, where the upright and the arms of the cross met, she could see the glitter of the scratch marks.

‘N.H.’

‘Nadezda Halak. That is my sister’s.’

The photograph Halak had produced showed a young woman with shoulder-length, dark brown hair pulled back and tied behind her head. Her eyes were a warm brown, and her brows finely arched.

She wasn’t exactly pretty, though. Her skin had a faintly sallow tone, and her cheeks showed the signs of faint blemishes, the residue of some earlier illness, perhaps. And Fry thought Nadezda’s jaw was wide enough to have confused the anthropologist, if that had been all he had to go on. Nadezda was wearing a white nylon jacket, unzipped to reveal a T-shirt underneath. She was smiling, but not showing her teeth.

‘She was very unhappy in Slovakia,’ said Halak. ‘She was poor, we were all poor. But Nadezda had no hope of work. She watched the television, and she kept saying she wanted to go to England, or the USA. She had been married, but she was treated very badly by her husband. He beat her, and hurt her very much. Then she said she would get the money any way she could, and she would come to England to work. So that’s what she did.’

Fry watched his face as he said ‘any way she could’. She knew that many young women from Eastern Europe set off to Britain with high hopes, only to be sold into virtual slavery when they arrived at the airport, trafficked for their bodies.

‘Sir, I have to ask you this,’ she said. ‘Was your sister a prostitute?’

Halak became distressed.

‘No, no. She was a worker, an honest worker. She went where she could make money. But a prostitute? No, never.’

Before he left the station, Fry asked Mikulas Halak to agree to a buccal swab. A DNA sample would enable the lab to confirm whether he was indeed related to Victim A, and how closely.