‘If you want to know why it’s because I’ve got cancer,’ he said. ‘So I’d be grateful if you don’t waste too much of my time.’

Marsden nodded. ‘I’m aware of your condition, Roy. I was—’

‘Only my friends call me Roy,’ Slack cut in. ‘And since you’re not my friend you can show me some fucking respect and call me Mr Slack. Or even sir.’

The detective’s jaw tightened and bulged, and Slack wound him up still further by grinning broadly.

‘I’m glad you think this is funny because I don’t,’ Marsden snapped. ‘Three more people were shot last evening and one of them, a police officer, is dead.’

Slack shrugged. ‘So I heard. But don’t tell me that you think it was me in that sexy leather outfit riding the motorbike?’

‘We’re not stupid,’ Marsden said. ‘We know that your grimy hands are all over this, despite your denials.’

‘Is that right? Then I take it you’re here because you’ve come up with the evidence to charge me.’

Marsden gritted his teeth. ‘We will eventually. Make no mistake about that.’

‘Well, you need to get a move on,’ Slack said. ‘I’ll be dead and buried in a matter of months.’

The detective looked as though he was going to lose his temper. His eyes flared and his bottom lip trembled.

His colleague put a hand on his arm and murmured something in his ear.

The lawyer took this as his cue to intervene, and said, ‘I’d like to remind you officers that my client is allowing himself to be interviewed voluntarily even though it’s the fourth time in just over a week that you’ve questioned him. So unless you get on with it I’m going to advise him to ask you to leave.’

Marsden sat there fuming while Detective Stanford began the interview. The first question was: ‘Why didn’t you inform us that Terry Malone was your son?’

Slack feigned surprise. ‘How did you find out about that?’

‘That’s not important. You should have told us.’

‘Why?’

‘Because it’s relevant. You’re a suspect in the disappearance of the police officer who shot him.’

‘And I’ve already told you that I know nothing about that.’

‘We don’t believe you,’ Marsden piped up, his tone aggressive. ‘You were Malone’s dad. It’s bleeding obvious that you decided to get revenge.’

‘Revenge is a mug’s game, and I’m not a mug,’ Slack said. ‘But if you reckon I’ve lied to you then feel free to produce the evidence.’

For the two detectives it was all downhill from then on. They pressed him again about the text messages sent to members of the task force and their families. And about the murders of Dave Prentiss and Marion Nash, and the shootings in Balham.