Page 51 of The Mercy Chair

‘Benford’s Law makes predictions about the frequency distribution of the first digit in large numerical data. If the first numbers were distributed uniformly, numbers one to nine would appear approximately eleven per cent of the time. But Benford’s Law proves that number one appears first thirty per cent of the time, while number nine is first less than five per cent of the time. The number two is less likely to appear first than the number one, but more likely than three. This pattern continues all the way to nine. It’s often used to detect fraud. Obviously, you and Poe are too dumb to understand the maths, so I won’t bother explaining it.’

‘Aw,’ Poe said.

‘So if Cornelius had chosen those numbers himself, he’d have selected more random numbers?’ Linus said.

‘Exactly. But in these alphanumeric strings, the number one appears first fifty per cent of the time. They therefore comply with Benford’s Law of real-life sets of data. That means they are real alphanumeric strings, not invented ones.’

‘I doubt it was anything like passwords anyway,’ Poe said. ‘We’ve seen his room. There was nothing electronic in it.Iprobably know more about computers than Cornelius Green did.’

Bradshaw frowned. ‘Or at least the same.’

Nightingale hid a smile. Doyle openly guffawed.

‘Best guess as to what they are then?’ Poe said, ignoring them.

‘I think this is a locally developed categorisation system, Poe,’ Bradshaw said. ‘Without more data there is no way to decode it.’

‘Something to ponder,’ Poe said. He faced Doyle. ‘They look homemade; was this what made them stand out?’

‘It wasn’t,’ Doyle replied. ‘Look again. And think about where they are on the body.’

He did. One was on Green’s left thigh, two were on his right and the remaining three were on his lower torso, just above the groin area. All six were oblique rather than parallel. Poe frowned. He tilted his head and looked at them from a different angle. ‘They’re upside down,’ he said eventually.

‘Because?’

Poe paused, but only for a second. ‘Because he tattooed himself.’

Doyle winked. ‘I knew there was a reason I’m marrying you.’ She faced Nightingale and said, ‘I took the liberty of sending the photographs to a forensic handwriting expert I know. It was his email I was waiting for. He confirmed that the formatting and the line and letter forms is the same on all six exemplars—’

‘Exemplars?’

‘What he calls samples. He confirmed that the same person wrote all six samples. That they are upside down, and on parts of the body Green could easily reach, supports our hypothesis.’

Poe nodded. He didn’t doubt for a moment that Cornelius Green had tattooed himself and he could think of only one reason to do that. ‘He didn’t want a record of them anywhere. Didn’t want a tattooist remembering them. Tattoos like this stick in the memory.’

‘They must be there to remind him of something,’ Nightingale said. ‘Something he couldn’t risk forgetting.’

Poe considered that. Decided there was a more probable explanation. ‘Or they’re a memento.’

‘A memento of what though?’

‘Nothing good,’ he replied.

Chapter 46

With the post-mortem over, they had said goodbye to Doyle over the Perspex barrier that separated the viewing area from the post-mortem room. Doyle was still wearing full barrier PPE, so Poe was at least spared having to kiss her goodbye in front of a grinning Nightingale.

‘See you for tea?’ Doyle asked.

‘If I can,’ Poe replied. ‘I’ll text you.’

Nightingale was needed back in Cumbria. She took the note that had been left under Poe’s windscreen wiper. ‘I’ll arrange for this to be forensically examined,’ she said. ‘What are your thoughts on it, Poe?’

Poe shrugged. ‘Although they weren’t as batshit crazy as I’d been led to believe, a close-knit community like the Children of Job is the perfect breeding ground for resentment to build up. It’s possible someone saw we were cops—’

‘Linus isn’t a police officer, Poe,’ Bradshaw nipped in.

‘Great point, Tilly. It’s possible someone sawsomecops and decided to get even on a long-held grudge.’

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