‘For a knot like this,’ Darby said, ‘our guy had to have used two strands of rope.’

Coop nodded. ‘You notice anything else about the furrows?’

‘Yeah. I’m not seeing the typical abrasion patterns.’

Williams spoke up. ‘You guys mind explaining that?’

Coop put down his camera. ‘When you strangle someone,’ he said, moving behind Samantha Downes’s chair, ‘generally you’re using a single piece of rope. You stand behind them and twist. Maybe you even go so far as to loop one end of the rope underneath the other – like you do when you tie a shoe – and then you give it a sharp tug to maintain more pressure around the neck.’

‘Okay.’

‘You’re holding on to the rope, tightening it, and the victim’s struggling. Doesn’t matter if the vic is bound to the chair, he or she is still going to struggle. She’s twisting her head this way and that, you’re pulling the rope, tightening it – maybe even pulling the rope up towards you, depending on your height. Either way you’re going to see abrasions around the furrows – the result of the rope slipping and sliding around during the struggle. With the daughter and the mother, there are barely any abrasions.’

‘Meaning our guy wasn’t holding on to the rope while she struggled,’ Williams said.

‘Correct. This knot our guy used, I think it was already in place – meaning the rope was already tied around her throat.’ He placed his hands near Samantha’s ears. ‘Then he grabbed each end of rope and gave it a hard yank.’ He jerked his hands sideways and outwards. ‘The knot did the rest.’

Williams looked at Darby and said, ‘Guys who are into this shit, my understanding is it’s the rope that gets them off. They prolong the strangling, wait until the vic passes out and then revive her so he can do it all over again.’

‘That’s true. Watching them suffocate, though, could be what gets our guy off. You find semen at any of the scenes?’

Williams shook his head. ‘Forensics did a thorough job. They checked the floors, the vics and their clothing, nothing.’

‘What about the bed-sheets?’

‘Sent them to the state lab, figuring he, I dunno, rolled around in them or something. They found dried semen stains but they all belonged either to the husband or to the daughter’s boyfriend. If our guy’s getting his rocks off in the homes, he’s real careful about it.’

Darby moved into the bathroom. The vanity had his-and-hers sinks. She removed her facemask, leaned close to the sink and sniffed. Williams watched her from the doorway.

‘What’re you looking for?’

‘Bleach,’ Darby said, and turned to the other sink.

‘You think he tossed one off here and dumped bleach down the drain to destroy the DNA?’

‘Maybe. I worked a case back in Boston where a guy broke into an elderly woman’s house. After he strangled her, he went into the bathroom, ejaculated into the sink and tried to wash it away with bleach. You or the forensics guys find bleach at any of the other crime scenes?’

‘No, but I’ll recheck the forensics reports just to be sure. Speaking of which, I’ve got one of my guys making copies for you, pictures and everything. You’ll have them later today.’

‘Thanks.’

‘I don’t think our guy would have had his own one-on-one private party in the bathroom. He’s got too much restraint.’

‘You’re probably right. I don’t smell any bleach, but we’ll take apart the drainpipes and swab them just to be sure.’

Darby ran the blue beam of her forensic light across the vanity and sinks. Nothing fluoresced.

When she turned her attention to the toilet, its seat lifted, the bowl glowed with faint green dip marks.

9

Darby frowned, thinking.

Bleach wouldn’t fluoresce unless it had been sprayed with luminol. When that chemical reacted with bleach, it gave off a blue glow. Here inside the toilet she was seeing a dull green glow. Some chemical other than bleach had been dumped inside the toilet.

But what? She doubted the killer had brought his own stuff to clean up with. More than likely he had used something here inside the house.

Darby examined the floor around the toilet. Nothing fluoresced, but she found a residue of a white, powdery substance. It definitely wasn’t talc; this was more granular. After she collected a sample, she placed an evidence marker next to it, got to her feet and moved to the linen closet across from the shower. She used a pen to open the bi-fold doors.

Five shelves. The bottom two packed with an array of cleaning products bought in bulk from a warehouse club like Costco. Darby went down on one knee and, with her gloved hands, rooted through the rolls of paper towels, cans of disinfectant, and bottles of Scrubbing Bubbles, Mr Clean, Windex and Clorox.

In the far back of the bottom shelf, tucked against the wall and hidden behind rolls of toilet paper, she found a blue bucket with a handle.

Darby removed the bucket. It was dry and empty, and it didn’t smell of bleach. When she ran the forensic light inside the bucket, dull green patches glowed from the plastic walls.

‘Did he use that bucket?’ Williams asked.

‘Maybe. Why else hide it in the far back of the bottom shelf, behind all the rolls of toilet paper? The bucket and the toilet have the same green glow.’

‘Bleach?’

‘No. Something else.’

Darby rooted through the rows of chemicals on the shelves and in the cabinets underneath the sink. Then she returned to the bedroom. While Coop set up his camera to take close-up shots of the victims, she ran the forensic light across the hardwood floor and walls, the victim’s clothing, the bedding and furniture. The blood appeared black in her goggles.

The wall to the right of the ivory armchair glowed with dull green patches. She found more green patches and smears on the skirting board, and in and around the chair.

‘This is where he cleaned up,’ Darby said. ‘He wiped down almost everything in this corner.’

She told Coop and Williams about the green marks she’d found inside the bathroom.

‘Bleach doesn’t fluoresce under an FLS unless it’s been treated with something like luminol, Coop said.

I found a bottle of Mr Clean in the linen closet,’ Darby said. ‘That product does react to FLS – it glows green. The marks along the wall and floor are faint, which, if I had to guess, means that there was a faint residue of Mr Clean or something similar in the bucket – and he moved the chair to clean behind it. I found a few drip marks along the side and the back – splash marks from when he used a rag or sponge or whatever to wipe down this area. He moved the chair so that he could clean the wall, floor and skirting board with a rag or sponge. Whatever he used, I didn’t find it in bathroom trash can.’

‘Might have used the Mr Clean, or taken it with him.’

‘But not the bucket. Decided to hide it instead.’

Outside, Darby heard an approaching car engine.

Williams had heard it too. ‘Probably some of my guys,’ he said, shutting his notebook. ‘Them, or the coroner. Excuse me.’

Coop was on his knees, his gaze roving across the wall and floorboards.

‘What the hell would he be cleaning up here, in this corner?’ he said, more to himself than to her.

‘I don’t know,’ Darby replied. ‘But we’re going to tear this room apart until we find out.’

10

The two agents on loan from the Denver office were a Mutt-and-Jeff pair named Eric Hayes and Victor Ottaviani. Hayes was the short one. He had piercing blue eyes and short and shaggy blond hair, and, while his sharp black suit had been tailored for his pencil-thin frame, Darby thought he looked like a skateboarder who had dressed up for a court appearance.

Ottaviani – Otto, as he liked to be called – was the polar opposite. He was an inch or two shy of six feet and he had a shaved head and a sizeable paunch. His eyeglasses had metal frames that were considered out of style in the eighties, and he wore a drab navy-blue suit that, had it been donated to either Goodwill or the Salvation Army, would have immediately been tossed into the ‘discard’ pile.