‘It’s not kerosene,’ she said. ‘If it was, it would fluoresce a light blue.’

‘What do you think it is – some sort of cleaner?’

‘Maybe. The film, though, looks like it has an oily residue. Could be cutting oil. If you can isolate the chemical components in your lab, we might be able to pin down a particular brand. Cutting oils are usually specialty items sold in stained-glass stores.’

Darby made a note on her clipboard.

When they finished taking pictures and making notes and sketches and measurements, they moved upstairs to meet the dead.

7

Darby entered the bedroom and stood stock still, an almost electric charge humming through her blood. She ignored the carnage at the foot of the bed and took in the cold, square-shaped room of white walls and blond-hardwood flooring.

Three windows in here: the one next to an ivory leather armchair was cracked wide open and none of the shades were drawn. She could see and hear the trees swaying and rustling in the wind.

To her left was the door to a small walk-in closet. A silver-framed charcoal-pencil drawing of the daughter, Samantha, done when she was a toddler, hung on the wall next to a built-in bookcase, the white-painted shelves stocked with books on art and on country decorating. She also found popular mystery and thriller novels by Dan Brown, Michael Connelly and Gregg Hurwitz.

The nightstand on the left side of the queen-sized bed held an alarm clock and a pile of cooking magazines, the top one an old copy of Gourmet. Everything – the white ruffled comforter and blood-red decorative throw pillows – like the daughter’s bedroom downstairs, was perfectly in place.

Was it possible the killer suffered from some sort of obsessive-compulsive disorder, or that the act of making the beds was a bizarre ritual that he felt compelled to perform? Sure. But she didn’t put much stock in it: Darby believed the act of making the beds contained no significance other than that the killer wanted to screw with their heads, maybe to throw them off the scent.

On the right side of the bed and set against the wall was a bureau made of dark cherrywood. On top, three more framed pictures: Samantha as a toddler, wearing a diaper and standing in a paddling pool; Samantha on a swing, her bony kneecaps covered in Band-Aids; Samantha standing on the grass and looking in surprise at something out of shot. The nightstand on the right – the husband’s – held a first-generation Kindle and an iPad, the latter’s smartcover, which doubled as a stand, holding the device upright.

Darby made detailed notes, sketched the crime scene and took preliminary measurements, while Coop began the laborious process of taking establishing photographs of the bedroom.

Finished, she moved to the foot of the bed and met the Downes family.

Daughter, mother and father were bound to the dining-room chairs with plastic zip ties. Samantha, barefoot and wearing a pair of old blue sweatpants and a white baby doll T-shirt, was seated across from her parents. The tee had been pulled down to expose her breasts.

The parents were also dressed in their nightclothes – Laura in a heavy red and black flannel nightgown, David in boxers and a dingy white undershirt with perspiration stains under the arms.

Both the mother and daughter had been strangled; their faces had a bluish pallor from oxygenated blood. Darby couldn’t see the father’s face; it was hidden behind a black garbage bag that was tied around his neck.

Like her father, Samantha had been bound to one of the dining-table’s carver chairs, their forearms secured against the wood of the armrests. The zip ties, three pairs used on each arm, had cut through the skin, the result of the victims’ violent struggle against their restraints. The zip ties used to secure their ankles to the chair-legs had also cut through their skin. One thing was clear: David Downes had struggled rabidly against his restraints. The zip ties along his forearms and ankles had cut deeply through skin and muscle, with drops and tiny pools of blood collecting around his limp hands and bare feet.

At one point during the struggle the chair had toppled backwards. On the carpet she found a clear pair of smeared, bloody handprints. They overlapped each other, and between them was a crusted, amœba-shaped smear, which suggested the killer had lifted the chair back up rather quickly. Why? Why not leave the husband thrashing about on the floor?

The mother was tied down to a side chair: because it lacked armrests, her wrists had been bound behind her back and secured to the chair’s rear legs with zip ties. As with her daughter, a strip of duct tape had been strapped across her mouth. But there was a difference: here, the tape hadn’t been removed during the course of the torture. Darby had seen slight abrasion marks on Samantha’s cheeks, a clear result of the tape having been yanked off. The killer had replaced the tape crookedly, all of which suggested that he had wanted the parents to hear their child screaming for help, screaming for the pain to stop. Then, most likely after Samantha was dead, the killer had replaced the tape over her mouth.

Darby thought about the order of the murders.

Sexual sadists usually focused their attention on their female victims. Darby suspected the killer tied the bag around David Downes first and then went to work on Samantha and Laura, most likely saving the daughter for last. Samantha was younger. Prettier.

Darby glanced to her left. On the wall near the doorway to the master bathroom was a dual digital thermostat. The heat for the second floor was on, set at 70°F. The second temperature, the actual one for the room, read 58°. The parents must’ve forgotten to shut the heat off before they turned in for the night, she thought, and poked her head into the master bathroom. It had white tiles and white walls and two windows set over a small jacuzzi. Everything in there looked neat and orderly and clean.

Had the killer cleaned up in the bathroom after the family was dead?

Darby moved behind Samantha’s chair and examined the young woman.

‘Coop.’

8

Darby pointed to a pair of burn marks along the side of the woman’s scalp.

‘Look like Taser marks,’ Coop said.

‘I agree.’

‘So the guy sneaks into Samantha’s bedroom, and while she’s sleeping he hits her with the Taser. During those few seconds when she’s incapacitated, he binds her wrists and tapes her mouth shut.’

‘Then he goes upstairs and subdues the parents.’

‘To get everyone to co-operate, he had to have had a gun.’

Darby nodded. ‘Binds and gags everyone in the bedroom, then goes downstairs and brings up the chairs.’

Coop pointed to the red dots covering the right side of Samantha Downes’s face. ‘We’ve got numerous petechial haemorrhages, which are consistent with strangulation.’

‘Face is cyanotic above the noose imprint,’ Darby added.

‘Could you explain that?’ Not Coop – Detective Williams. He had entered the bedroom, wearing booties, latex gloves and a paper facemask.

Darby said, ‘Cyanotic refers to the blueness you’re seeing in the face – lividness caused by imperfectly oxygenated blood.’

Darby studied the furrows the rope had left on the young woman’s neck. As was most often the case with strangulations, the rope had left its weave imprinted on the skin.

‘Weave looks like a braided pattern.’

‘My money’s on a nylon rope. Look under the chin.’

Darby did. ‘Figure-eight pattern.’

‘That’s probably from whatever knot he used. But here’s where it gets weird. Look at the back of the neck.’

Darby studied the mark. ‘It’s a single, braided twist,’ she said.

‘And those same figure-eight patterns are underneath each ear.’

‘Definitely not your standard noose.’

Darby moved to the mother. Laura Downes had exactly the same rope imprints on her skin, in exactly the same locations.