Fabel extended his hand. ‘Herr Doktor Stern. Thanks for your time.’

‘No problem.’ Stern reached into the chaos on his desk and pulled out a file. ‘I made you a copy of the report I drew up for the local police.’ Stern nodded in the direction of Sülberg, who had entered the office.

‘Thanks.’ Fabel took the file but did not examine it right away. ‘Would I be right in assuming that the girl was drugged with Rohypnol?’

‘Drugged, yes. Rohypnol, yes. But not on its own. As I’ve stated in the report there are only very faint traces of Rohypnol in her blood. Rohypnol metabolises slowly … it tends to hang around in the bloodstream for several hours after ingestion.’

‘Could it be that the dose was enough to daze her but light enough to have all but disappeared by now?’

It was Susanne who answered. ‘No. Even after it has disappeared from the bloodstream it can be traced as a metabolite in urine for more than seventy-two hours.’ She turned to Stern. ‘I presume you checked urine samples?’

Stern nodded. ‘We checked for seven-aminoflunitrazepam in her urine. Very faint residual traces. As Frau Doktor Eckhardt pointed out, if Michaela had been heavily drugged with Rohypnol within the last three days then we would have found more significant traces.’

‘But she was drugged?’ Fabel asked.

‘Absolutely. Michaela had faint chemical burns – and I mean very faint, more of a dermal inflammation in her mouth and throat. And when I asked her about the windows of clarity she had during her altered state, she talked about how unafraid she had felt.’

‘Of course,’ said Susanne. ‘Some kind of cocktail that included gammahydroxybutyrate?’

‘Probably …’ Stern shrugged. ‘But gammahydroxybutyrate metabolises so fast that I have no traces to prove it …’

‘Gamma what?’ The conversation was going too fast and getting too technical for Fabel.

‘Sorry.’ Stern made an apologetic gesture. ‘Gammahydroxybutyrate, GHB. Otherwise known as Gook or Zonked.’

Again Susanne picked up the thread. ‘A particularly nasty central-nervous-system depressant. It does the same job as Rohypnol but is potentially much more dangerous. It was, believe it or not, sold until recently in health-food shops as a bodybuilding aid. It really has little medical application, so the majority of production takes place illegally.’

‘And because it is made in illicit labs with no controls,’ continued Stern, ‘there are wild variations in purity. Often the chemicals used to synthesise and stabilise it are highly toxic.’

‘And you think it was the toxic chemicals that caused the burns in her mouth?’ Susanne asked.

‘Yes … and GHB can also have very strange side effects. Even light doses can cause nausea, vomiting, delusions, hallucinations, seizures and, of course, loss of consciousness. One side effect can be a feeling of fearlessness, such as Michaela says she felt. If she was given a cocktail of either flunitrazepam or clonazepam with gammahydroxybutyrate, the risks of general anaesthesia, respiratory depression and even coma would have been very high indeed. Michaela is lucky that she isn’t on a respirator. As Frau Doktor Eckhardt says, GHB is a particularly nasty little product. Whoever did this used it in combination with other drugs that would have a synergistic effect on each other. They may not have been trying to kill their victims, but they didn’t particularly care if they survived the experience.’