‘We’re working with the authority of the Ministry for State Security,’ insisted Tilsner. Müller had to resist raising a quizzical eyebrow. ‘If you’d rather speak to them direct, person to person, to explain how you came to be obstructing a murder inquiry, I’m sure they’d be interested.’

The man sighed, and leant forward on his elbows. ‘I’m not being deliberately obstructive, Comrade Oberleutnant. But there are procedures we must follow. Unless you have a signed authority from the Ministry for State Security, you will have to put all your questions in writing for consideration in due course.’

Müller fully expected Tilsner either to give up at this point, or lose his temper and start resorting to physical threats. Instead, her deputy reached into his coat pocket and brought out an envelope.

‘Here’s the authority,’ he said, handing it over to Frank. As the man studied it, Tilsner winked at Müller. She frowned back. I’ll explain later, he mouthed.

The man pushed his glasses up his nose and steepled his hands together. ‘This seems to be in order. You obviously have friends in important places.’

‘No,’ said Müller. ‘It’s simply that this is an important murder inquiry.’

‘Very well,’ said Frank. ‘What is it you need to know? And I hope it isn’t Frau Rolf who’s been murdered?’

‘It isn’t,’ said Tilsner.

‘Who then?’ asked the man.

‘Ah,’ said Müller, turning the tables. ‘Well that’s something we’re not permitted to discuss.’ The fact they still didn’t know the identity of the victim, despite already being a couple of days into the inquiry, wasn’t something he needed to know either. ‘What we want to know is why Lotti Rolf ceased to be employed here?’

‘It was partly health reasons, partly disciplinary reasons.’

‘You’ll have to give us more than that,’ said Tilsner.

The man sighed. ‘She developed a serious health condition.’

‘Surely that’s not enough to sack someone?’ queried Müller.

The man shuffled in his seat. ‘No, it’s not. Not normally. But then she started to make a song and dance about it.’

‘In what way?’ asked Tilsner.

‘Writing petitions about the health conditions at the mine, that sort of thing. Making a nuisance of herself. Given you say you’re working in conjunction with the Ministry for State Security, I’m surprised you don’t know all about it already. They certainly do. If you need to ask them anything, try the regional headquarters in Dresden. Now who was it who was looking after it?’ He pulled a pocket diary from his jacket and flicked through it. ‘Ah yes, a Major Bahlow was the man in charge.’

Müller and Tilsner exchanged knowing looks. Bahlow seemed to have a piece of meat in every bowl of soup.

‘So what was her health condition?’ asked Müller.

‘Lung cancer.’