A mattress was leaning against one of the glass walls, a king-sized bed still wrapped in courier’s cellophane and bearing the purple and orange FedEx markings.

‘That’s their bed?’ I said. ‘His wife sent their bed to his office?’

‘Mrs Buck returned home early from a business trip and discovered Mr Buck with the housekeeper.’ Mallory frowned with embarrassed disapproval. ‘And he wasn’t helping her to unload the dishwasher. So Mrs Buck went for Mr Buck with an oyster knife.’

‘An oyster knife?’

‘Yes, an oyster knife. It has a short, broad blade. These are affluent people. They like oysters. Anyway, she threatened to cut his testicles off and shove them up his back passage. Responding to sounds of a violent struggle, the neighbours call 999. Officers restrain both of them. Mr Buck hasn’t slept at home since.’

We looked at the marital bed in its FedEx wrapping.

‘You think the wife did this, sir?’ I said.

Mallory shrugged. ‘Right now she’s all we’ve got. She’s on record as making a threat to remove her husband’s testicles.’ He looked down at the banker’s mutilated throat. ‘Although nobody’s aim is that bad.’

‘She may have delegated,’ I said. ‘She has the money to hire someone good.’

‘That was my thought,’ Mallory agreed. ‘But then there would be glove prints. And we can’t find any glove prints. And unless she hired someone who didn’t have any idea what they were doing, there should certainly be glove prints in this room. As you know, glove prints can be as distinctive as fingerprints. If the gloves are thin enough, fingerprints can pass through the material. Fingerprints can also be present inside the gloves. Few villains take their gloves home, preferring to ditch them close to the crime scene. So we’re looking for a pair of gloves as well as glove prints.’

‘And what happens if we can’t find glove prints?’

‘Then we have to eliminate every print in the room.’

I looked again at the photograph on the desk. And I could see it now – the boy the man had been. Hugo Buck was standing on the far right of the photograph and one tiny spot from the spray of blood had flecked his image. Twenty years had gone by but the smooth good looks of the future banker were there, buried under a shallow layer of puppy fat. The boys become the men, I thought, and the living become the dead.

‘Did you see his hands?’ Mallory said.

Buck’s hands had fallen by his side but still gripped the vial of pills he had been holding in the last moment of his life. It was another thing I was seeing for the first time.