‘Of course I am. I’ve never killed anyone, and I don’t understand why you think—’

‘How do you explain your DNA being at the properties of every one of the five victims then?’

‘Because I fitted the alarms at all the different properties. I’ve already told you this.’

‘Not very good systems then, were they, Mr Kent, if the killer managed to bypass every one of them?’ said DCI MacLeod.

‘I thought they were.’

‘My client’s not being questioned about his skills as an engineer, now is he?’ Jacobs looked at MacLeod over his half-rimmed glasses with the gravitas of a man twice his age.

MacLeod wasn’t deterred. ‘Don’t you think it’s a bit of a coincidence that every one of our five victims had their brand-new alarms fitted by you? What do you reckon the odds of that are?’

‘Look, I’ve fitted thousands of alarms over the years. I’m a hard worker. I can do two or three clients in one day, so the odds probably aren’t that great.’

‘What about the odds of the killer being able to bypass every one of your alarms?’

Again Kent protested his innocence, and again Jacobs intervened with the same objection — that it wasn’t his client’s work-related capabilities that he’d been arrested for.

‘So, how come your DNA was found in four of the victims’ bedrooms if you were only fitting the alarms?’ Tina asked, keen to move the interview on.

‘I had to have access to the whole of each property while I was doing the work, because I needed to fit sensors in different rooms.’

‘But you didn’t fit sensors in any of the victim’s bedrooms. We checked. Nor did any of your employers think you should have been in them. So what was your DNA doing in there?’

‘I don’t know,’ answered Kent. ‘Maybe it got carried in there somehow from other places in the house. Is that kind of thing possible?’