‘It’s not unthinkable, but you can have similar problems to lime, really. You’d have to find the right acid mix for starters, and you’d have to be able to either buy it or mix it in sufficient quantity to allow it to do its work properly, which may well leave an evidence trail in itself. Then you’d need a way of disposing of all the acid afterwards without arousing suspicion. John Haigh tried it. You heard of him?’

‘Actually, yes,’ Dani said, feeling a slight triumph. ‘The Acid Bath Murderer.’

‘Indeed.’

‘But wasn’t his method almost foolproof?’

‘Almost, yes. When the police first took an interest in him, it wasn’t because they thought he was a murderer at all. They were pursuing him for theft and fraud, and when searching his workshops they found belongings of his victims. He eventually confessed to the murders.’

‘So if he hadn’t been stupid enough to be involved in petty crime, and if he’d not kept those belongings, he may have gotten away with it.’

‘Maybe. Maybe not for much longer though. The acid he used to dissolve the corpses turned into a thick sludge. Bodies don’t just disappear in acid, they dissolve into it. Haigh stored the sludge in oil drums. I’m not sure of the overall effectiveness of the method, to be honest. That sludge is going to be pretty suspicious to say the least, unless you use a vast quantity of acid in the first place so that it remains dilute enough to dispose of easily. Plus there’s the risk that some body parts would remain. Teeth, bone. Gall stones or kidney stones, if the victim was unlucky enough to have such afflictions, as was the case with one of Haigh’s victims.’

Grant finished his spiel. Dani’s brain was working overtime going over what he’d said, and trying to make sense of it all.

‘Bodies can be fed to animals,’ Grant said, as though thinking out loud now, and warming back into his role once more. ‘Plenty of animals, pigs for example, will crunch through bones happily enough.’

‘Like Robert Pickton?’ Dani said. Grant gave her an impressed look.

‘Exactly. He was thought to have killed as many as forty-nine women. Many he fed to his pigs, but it was also alleged that he minced some of the victims and sold their remains as meat.’

Dani winced at the disgusting words.

‘In his case, some DNA traces of the victims did still remain. Pigs won’t clean up every last morsel, or every drop of blood. They’re messy animals. And some of the bone fragments, teeth, would pass through in the pigs’ faeces, but it would still take a lot of effort to identify those traces and match them to victims. To all intents the bodies have disappeared.’

Dani thought about that one.