With most river and harbour diving everything had to be done by touch, so she had to be patient, allow the thing to feed its shape from her fingers up her arm, download an image in her mind. She palpated it gently, closing her eyes, counting the fingers to reassure herself it was human, then worked out which digit was which: the ring finger first, bent away from her, and from that she could figure out which way the hand was lying — palm upward. Her thoughts raced, as she tried to picture how the body would be — on its side probably. She gave the hand an experimental tug. Instead of there being a weight behind it, it floated free of the silt, coming away easily. At the place where a wrist should be there was just raw bone and gristle.

'Sarge?' PC Rich Dundas said, into her earpiece. His voice seemed so close in the claustrophobic darkness that she startled. He was up on the quay, tracking her progress with her surface attendant who was meting out her lifeline and controlling the coms panel. 'How you doing there? You're bang over the hotspot. See anything?'

The witness had reported a hand, just a hand, no body, and that had bothered everyone in the team. No one had ever known a corpse to float on its back — decomposition saw to that, made them float face down, arms and legs dangling downwards in the water. The last thing to be visible would be a hand. But now she was getting a different picture: at its weakest point, the wrist, this hand had been severed. It was just a hand, no body. So there hadn't been a corpse floating, against all physical laws, on its back. But there was still something wrong about the witness statement. She turned the hand over, settling the mental picture of the way it was lying — little details she'd need for her own witness statement. It hadn't been buried. She couldn't even say it was buried in the silt. It was just lying on top of it.