The temperature was kept just above zero in here. Beyond an impatience to get started, I felt nothing when I looked at the bodies. Their spirits had flown. Now there were just the living in this freezing room, and two brutalised empty husks.

‘The four questions of death,’ Elsa Olsen continued. ‘Cause? Mechanism? Manner? Time?’ She smiled pleasantly. ‘Death’s fifth and final question – who? – I leave to you gentlemen.’ A smile for DI Whitestone. ‘And lady.’

Elsa stepped between the two steel tables.

‘Cause of death for both men was suffocation,’ she said.

Mallory said, ‘They didn’t bleed to death?’

Elsa shook her head. ‘The single wound to the neck caused a massive haemorrhage. Death would have been quick, quiet and messy. An initial spray, perhaps several, as the artery was cut and then massive bleeding. As you noted, DCI Mallory, the trachea was severed, so screaming was a physical impossibility – there was nothing left to scream with. But it wasn’t just the trachea that was cut. The carotid artery was also severed along with the internal jugular vein. Death would have been almost immediate, but neither man had the chance to bleed to death. They suffocated before they had the chance to bleed out.’

Elsa spoke the effortlessly perfect English of the Scandinavian abroad. She was fortyish, Norwegian, tall and slim and dark, one of those black-haired, blue-eyed Norwegians who defied the Nordic stereotype. Mallory had told me that she was his favourite pathologist because she talked about the dead as if they had once been among the living. He said they did not all do that.

‘We don’t have a weapon,’ Mallory said. ‘We don’t even have an idea of a weapon. What kind of blade can cut a throat like that, Elsa?’

‘The mechanism would need to be long and thin and razor-sharp,’ Elsa answered. She peered at the gaping black letterbox in Hugo Buck’s neck which extended from ear to ear. ‘The assailant was standing behind the victim, as we can see from the classic long sweep of the wound. The mechanism would be something like a short double-edged sword, a long scalpel, something similar. Something with a sharp stabbing point and good cutting edges. These are remarkably clean cuts. A torn artery tends to contract and stem the bleeding. But a cleanly cut artery starts bleeding and it doesn’t stop.’ And then, almost as an afterthought, she said, ‘Manner of death was murder.’

‘Time of death?’ Whitestone said.

‘Hugo Buck had an algor mortis or temperature of death of ninety-seven degrees Fahrenheit,’ Elsa said. ‘Not far below normal body temperature of 98.6. Adam Jones was ninety-five degrees. But Mr Jones died on the street and Mr Buck died in a climate-controlled office.’

‘And bodies lose temperature more quickly in the open air,’ Whitestone said, looking at Gane.