‘Really, it could be anything. Maybe he suffered a loss, a tragedy that he blames someone for – or some thing, a company, organization, institution. The loss might’ve happened when the Bone Collector story hit the press and he embraced the idea of getting retribution the same way the Bone Collector did. He’s been carrying that thought around with him. That’s one explanation for why this murder echoes the attacks from a decade ago – some of those crimes were underground too, weren’t they?’

‘That’s right,’ Rhyme confirmed.

‘And your unsub has a morbid interest in the morphology of the human body. Skin, in his case.’

Sachs added, ‘Yes, I found evidence that he touched the victim in a number of places – not sexually. There was no reason related to the tattooing for that that I could see. It gave him some satisfaction, I was thinking. My impression.’

The doctor continued, ‘So, the first reason he might be interested in the Bone Collector: a psychological bonding with him.’ He chuckled. ‘An insight that, I suspect, is rather low in your estimation, Lincoln.’ He knew of Rhyme’s distrust of what the criminalist called ‘woo-woo’ policing. ‘But that might hint he too is out for revenge,’ Dobyns added.

Rhyme said, ‘Noted, Doctor. We’ll put it on our evidence chart.’

‘I think you’ll be more interested in the second reason he was interested in the chapter of this book. Whatever his motive – revenge or joy killing or distracting you so he could rob the Federal Reserve – he knows you’ll be after him and he’ll want to learn as much as he can about you, your tactics, how you think. How specifically you tracked down a serial criminal. So he doesn’t make the same mistakes. He wants to know where your weaknesses are. You and Amelia.’

This made more sense to Rhyme. He nodded at Sachs, who told the doctor, ‘The book is practically a how-to guide on using forensics to stop a serial criminal. And it’s clear from running the scenes that he’s been paying attention to scrubbing the evidence.’

Pulaski asked, ‘Doctor, any idea why this victim? There was no, you know, prior contact between them that we could find.’ He gave a brief bio of Chloe Moore.

Sachs said, ‘Seems to be random.’

‘With the Bone Collector, remember, his true victims were somebody else: the city of New York, the police, you, Lincoln. I’d guess that the choice of victim by your unsub is mostly accessibility and convenience – to have a place and the time to do the tattoo undisturbed … Then I think there’s the fear factor.’

‘What’sat?’ Sellitto asked.