His interpreters – one African specialist, one expert in Afghan dialogues, and one Arabic native speaker – can usually tell instantly where a person is from. "But if an immigrant refuses to speak, we have tricks like playing them the national anthem and asking them to sing it. Or when they say they are Palestinian, we show them a bank note and say 'How much is this?' Or if they say they are Somali, we say in French 'Where is your money?' – and when they go for their pockets, we know they are not Somali but from French Africa – probably from the Congo or Cote d'Ivoire.