Kevin brought their coffees and tiptoed out.

‘So, other than that,’ Rory continued, ‘our careful investigations have thrown up nothing at all. He wore gloves and left no fingerprints in any of the houses he visited.’

Jackman shrugged. ‘No more than we expected, I guess, but what about the crime scene in Connaught Road?’

Rory sipped his coffee and pulled a face. ‘The coffee never gets any better, does it?’

‘Nope,’ said Marie.

‘The crime scene is a little different.’ Rory wiped his lips with a tissue. ‘We suspect he spent some time there, even after he’d murdered Nancy Eliza Cutler. But let me get the sequence of events in order — I’ll start in that jungle of a garden.’ He took a breath. ‘As you said, Marie, it was no easy task. The Lost Gardens of Heligan have nothing on the Lost Garden of Nan Cutler. I reckon that patch last saw a lawnmower at the time of the Great War. That should have helped us because he’d have flattened the grass and so on, except that the neighbour ran amok in it and trampled most of the tracks and evidence. Still, we were able to find another print in the soft soil of a convenient molehill, and it matches the one we already have.’

‘Excellent. So that’s concrete proof it’s the same man.’ Jackman nodded.

‘Indeed. Now, he gained access through an open fanlight window in the downstairs toilet. It’s situated at the side of the house, and I suspect that as soon as the neighbour’s garden lights came on, he legged it around the corner of the building, wriggled his way inside and pulled the window closed behind him. That way the neighbour wouldn’t have seen him enter the house.’

‘So, if Eric and Lizzie Coupland had actually gone in to check on Nan, they would have run into the killer,’ Marie said.

‘Undoubtedly.’ Rory shuddered. ‘So perhaps it’s all for the best they didn’t. I could have had three bodies in my chiller cabinet, along with the nice little Italian bubbly that Sainsbury’s has on special offer this week . . .’

Marie snorted.

‘We believe he got in just after eleven p.m. and went immediately to prepare the tripwire. He used very slim pins, most likely the ones that come with picture-hanging fittings. They were driven in quite deeply and at an angle, in order to hold the wire firmly and not come loose when her foot caught it.’ He took another printout from the folder. ‘We examined the welt on the old lady’s foot and decided it was indeed wire that he used. In fact, after finding minute particles of metal fibres embedded in the welt, we deduced that it was actually picture-hanging wire. Electro brass-plated twisted steel wire to be exact.’ He sniffed. ‘Unfortunately, this can be purchased anywhere online or in the major hardware stores.’ He drank more coffee. ‘Anyway, we think he then went into the spare bedroom and took two items of clothing from the wardrobe there, and here, I am happy to say, we had some luck.’