‘What have people been saying to you, sir? Have you been hearing rumours? Please share any information you have.’

Lowther tilted his head. ‘I’ve got exceptional hearing, I’m told. I can hear the people in the next room now.’

Fry tried for a while longer, probing for information about his feelings towards Brian Mullen, and about the last time he’d visited the Mullens’ house in Darwin Street. But she could feel that she was getting nowhere. The conversation seemed to veer off in directions that she had no control over, and she didn’t know how to bring it back under control. She just didn’t have anything of substance to use against Lowther and pin him down.

When the interview was finally over, they watched John Lowther leave. Then Fry walked back and checked Interview Room Two.

‘There wasn’t anyone in the next room,’ she said.

‘So what was he hearing?’ asked Cooper.

‘I don’t know.’

‘Something outside? Someone chatting in the corridor?’

‘Maybe.’

‘Some people do have particularly good hearing. They say blind people develop their other senses to compensate.’

‘So what is John Lowther compensating for?’ said Fry. ‘Let’s face it, he’s unbalanced.’

‘Hang on, Diane. He could be faking it.’

‘Faking it?’

‘Well, all that stuff was verbal. It was like a smokescreen. He didn’t actually answer any of your questions, as I’m sure you noticed.’

‘A bit of a teacake,’ said Fry thoughtfully.

‘What?’

‘It was something Gavin said.’

‘Well, we shouldn’t underestimate Gavin’s judgement.’

‘I think I’ll get John Lowther’s background looked into,’ said Fry. ‘Faking it, or not.’

Listening to the interview tapes afterwards, Cooper noticed a pattern to John Lowther’s answers. Sometimes he spoke quickly, the words spilling out with no prompting. At other times, he was hesitant, leaving long pauses before he answered. During these periods, he seemed to ramble and go off at tangents, often failing to address the question altogether.

At other times, Lowther seemed eager to anticipate what his interviewer was going to say, and tried to complete her sentences for her, often guessing the wrong word from its initial letter or sound. It sounded like a verbal equivalent to the predictive text function on his mobile phone. Both produced gibberish too often to be any real use.

Cooper had heard this kind of language before. The sound of it brought back so many unpleasant memories that he knew he was reacting on an emotional level. He tried to suppress the response, to smother assumptions that might prevent him from being objective. These days, his antennae twitched at the first sign of aberrant behaviour in those around him. Right now, he was even more touchy on the subject, thanks to Matt and his obsessions. But not every eccentricity or verbal quirk was a sign of mental illness.