‘Possibly. Industrial or mechanical, almost certainly. Now that would be unusual for machinery. We must be careful to distinguish between compressive asphyxia, the kind a python would use on its prey, and its cousin traumatic asphyxia. Road accidents, where a vehicle occupant is crushed, say, underneath a lorry, are usually traumatic asphyxia: catastrophic pressure to the chest. The classic cases of traumatic asphyxia are seen where victims are trapped under vehicles that fell off hoists or ramps. In such cases you tend to see other crush injuries, which are not present on this victim. Gouges, grazes, puncture wounds as well. But in this case I would provisionally lean towards some kind of gradually applied but sustained mechanical force.’

‘I keep thinking of the victim being trapped in a net at a weir, or some industrial water intake,’ Gillard said.

‘I did too, initially. But there is no water in the lungs. As I’ve said, he didn’t drown. Despite the alluring fishing net ideas, we have to follow the forensics. While he may have still been alive when he was in the water, if so his head must still have been above the surface at the point of death.’

‘And he couldn’t shout for help because he couldn’t breathe.’

‘Precisely. But, as I say, that is just one possibility. He may well have been dead before his body hit the water. There is no way of knowing, forensically.’

‘The lack of clothing is interesting though,’ Gillard said. ‘If he wasn’t swimming, why wasn’t he clothed?’

‘Not my job to speculate,’ Delahaye said. ‘Now, about those cyanosed contusions. The mesh pattern, as you will have seen from the photographs, is pretty extensive. Whatever it was, he seems to have pretty much been wrapped in it. The pattern is regular and found on most parts of the body.’

Gillard said: ‘Trying to think about death prior to the river: maybe he was gradually rammed by a car into a chain-link fence?’

‘Possibly, but presumably there would be fence marks only on one side of him. Anyway, that’s your job to figure out. I can only describe to you what has happened to the body. I found quite an array of textile fibres in the nose and mouth, which I’m going to send off for testing.’ He paused and then asked. ‘Any progress on who he is?’

‘None at all that I’m aware of,’ Gillard replied. He pulled up the rather sketchy details that Cottesloe had produced so far. ‘He doesn’t tally up with any of the existing missing persons in our area in terms of appearance, and no one has called in to say he is missing in the last twenty-four hours. I suppose I had better order a mitochondrial DNA test so that we can look for relatives.’