‘Well …’ The profiler removed his thin-framed glasses, studied the lenses against the light, and put them back on. ‘The use of symbolism – anything from urban graffiti to sacred motifs – usually denotes allegiance to some kind of doctrine or code. The more vehement an individual’s belief in such things, the more likely he or she is to outwardly promote them. Some choose to preach; others get tattoos. Your killer, I’m afraid, appears to be expressing his views in rather more extreme fashion. Whether his conviction compels him to kill, or if he’s targeting those with opposing opinions, isn’t clear at this stage.’ He glanced over at the photo of the marking. ‘You say this sign means purified. That suggests he’s trying to cleanse his victims of something, be it particular beliefs, or responsibility for specific actions. Given what little we know, it’s impossible to say, but finding out more about this symbol and its origins may be the only way to establish his motivation, and move yourselves closer to apprehending him.’

There was silence for a moment before Amala asked, ‘So why was there no symbol at the first scene?’

‘Good question,’ Hunter said. ‘It may indicate a belief system that’s growing, rather than having been previously established. The killer may still be learning, either through his own research, or because he’s being coached.’

Hawkins frowned. ‘You’re talking about radicalization.’

‘Of a kind, yes.’ The profiler wandered across to the investigation board, began studying the photographs of the dead, speaking with his back to the group. ‘It’s possible that what we’re seeing is murder by proxy, a similar mentality to that of a suicide bomber conscripted by extremists. The bomber doesn’t see the whole picture, but he doesn’t need to; he just buys into the elements that convince him to do his master’s bidding without question. And if someone believes he’s expediting the will of a higher power, it’s possible to convince him of almost anything, even if it means inflicting death and suffering in the present, in return for supposed rewards on a subsequent existential plane.’ He turned back to face them. ‘If your murderer is acting on behalf of such an entity, be it imagined or otherwise, there’s really no limit to what he’s capable of.’

‘Great.’ Hawkins pinched the bridge of her nose. ‘So we’re going to see more killings.’

Hunter sighed. ‘That depends on what he’s trying to achieve.’

She took a few seconds to order her thoughts before going on. ‘Then as you suggest, our priority has to be finding out more about this symbol, and the belief system behind it.’ She looked at Frank. ‘We should start by looking into alchemy.’