Robin and Craig look at the distribution of the marks. Sharp’s are grouped closest to where his body fell, while Finn’s are all over the place. It looks like he was moving backwards and forwards across the van, each time walking through the blood.

‘And these?’ Craig asks, pointing up the window.

‘How much do you know about projected blood stains?’ Susie says. They both look blank. ‘You used to call it arterial spray.’

‘Start from the beginning.’

‘So, when an artery is damaged, the blood is emitted in a jet, if you like, which will hit any nearby surface or simply fall to the floor. These spots of blood on the floor are arterial rain.’ Robin winces at the term, although given what he’s seeing, it’s appropriate. ‘They project out by some distance. You can also see the separate spurts on the walls, landing dependent on how the victim is moving. Following?’

Craig and Robin nod obediently.

‘So, I can estimate it started here,’ she points to the wall, ‘then he turned to his left, distributing the blood in the pattern you can see here.’

Robin stares at the wall. He can see five distinct arcs of blood drops – some intact circles, others dripping down, running together.

‘Then he must have fallen, smearing and smudging as he went. The majority of the blood is pooled under the table, where the body was.’

She stares at the large dark red stain, her eyes narrowed. ‘I estimated about five litres in here. He bled out, right?’

‘That’s what the pathologist said, yes.’

‘Thought so. That’s most of his blood volume, right there, on the floor.’

‘Christ,’ Craig says under her breath. She inhales slowly, deeply, then faces the CSI again. ‘Any sign of anything else? Cast-off or impact spatter?’

Robin knows what she’s asking. Looking for the telltale signs of a weapon being brandished, or someone being beaten.

‘No, nothing. And that would tie up with the body, right?’

‘Right,’ Robin says, with a glare at Craig. Why is she looking for something that isn’t there? Aren’t things bad enough as it is? ‘And whose blood is this?’

‘DNA not back from the lab, but given the analysis on the victim’s clothes, my guess is this all belongs to Simon Sharp.’

They thank the investigator and walk silently away from the van. Out of the cordon they pull off their suits, Robin wrenching the mask from his face.

‘Christ,’ Craig says again. ‘Imagine being there when that happened.’

Robin doesn’t want to. The idea of watching, as someone bled to death in that way, is horrifying. He can understand why Finn’s brain is as scrambled as it is. Killer or not, it would have been traumatising to see. Flailing around the van, blood pumping from his neck.

Being covered in it, soaked in it.

Watching your friend die.

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