Otto went to help Coop dismantle the bathroom drainpipes and swab them for semen, while Hayes joined her inside the MoFo. Darby had worked in her fair share of vehicles billed as rolling crime labs, but she found them to be haphazard affairs, a desk or two with only basic forensics equipment hastily installed inside the back of a van or box truck.

Not so with this one. It was housed in a long semi-trailer, and everything inside, from the worktops to the equipment, had been carefully laid out. Smelling of fresh paint and metal, and with its strong lights, white counters and floors, and glass cabinets, it had a Steve Jobs/Apple store design vibe about it. Everything Darby saw looked showcase perfect, not a scratch anywhere. She wondered if this was the mobile lab’s inaugural run.

‘MoFo’s got pretty much anything you might need stocked in here,’ Hayes told her. The soundproofed walls filtered out the dull roar of the vehicle’s running diesel engine, but she could feel it rumbling beneath her feet. ‘You need any help, just shout.’

Hayes retreated to one end of the trailer to use the mass spectrometer, which would identify the composition of the oil from the sliding glass door and the white, powdery residue she had found on the floor near the toilet. Darby took the evidence bags holding the duct tape to a workstation equipped with a Superglue Fingerprint Fuming Chamber.

For the next twenty minutes Darby oriented herself with the equipment and the locations of the tools and chemical solutions. Hayes was right: pretty much everything she needed was inside the trailer, including a tank of liquid nitrogen. Perfect. She went to work on the tape.

In addition to fingerprints, epithelial cells, hair and dead skin, the adhesive side of duct tape also picks up an array of trace evidence. Darby examined all six strips for hair and fibres. She found plenty, along with a lot of blood. After meticulously collecting and labelling each sample, she made very detailed notes on her clipboard.

Duct tape is notoriously sticky. Even if a killer wears gloves, often the adhesive is strong enough to pull off a piece of a latex. Tucked into a torn edge of tape she discovered a sliver of latex half the size of a pencil eraser; on one ragged end was a nearly invisible, pin-sized black smear. After marking and photographing it, she used the tip of a knife to carefully prise it away.

Darby examined the smear underneath a microscope. Given what she saw, she suspected it was ink. The mass spectrometer would be able to identify the sample.

She placed black fingerprint powder, distilled water and washing-up liquid inside a glass beaker and mixed everything together using a fingerprint brush made of camel hair. She put it aside and, slipping on a fresh pair of gloves, moved to the nitrogen tank. She released the tank’s locking tab, removed the metal dipstick with the cone attached to the end and poured the liquid nitrogen into the stainless-steel container she had placed on the worktop near the sink.

Carefully she dipped the first strip of tape into the container. She separated the smooth layer from the adhesive side. The smooth layer went into the Superglue Chamber; the adhesive side went on a tray, where she worked the fingerprint solution she’d mixed into it. It went on thick and black, and, after the tape was completely covered, she carried it to the sink. The solution would stick to any fingerprints; the rest would wash away.

Darby held the tape under the running water.

No fingerprints. She bagged the tape and then went to work on the next piece.

‘That white powder you found on the bathroom floor?’ Hayes said. ‘It’s an aminoglycoside antibiotic called neomycin. Not the ointment for skin infections – I’m talking about an actual oral pill, which I didn’t even know existed. It kills bacteria in the intestinal tract. It’s used to treat E. coli infection and a condition called hepatic coma. That’s when the liver stops filtering out toxins and they build up in the blood. It’s also used to treat something called – I’m going to mangle this pronunciation – hepatic encephalopathy, which is a worsening of brain function that happens when the liver fails at removing the aforementioned blood toxins.’

Darby had just finished hanging the last smooth side of tape inside the Superglue Chamber when the back door opened. It was Otto.

‘Cooper wants you in the bedroom,’ he called out over the diesel engine.

‘I bet he does.’

His face coloured slightly. ‘I didn’t mean –’

‘Relax, I was just busting your balls.’

Hayes called out over his shoulder, ‘Hey, Otto, pause the sexual harassment and come on up here and give me a hand with this computer shit. The satellite feed just crapped out. Again.’

11

While Darby had been in the MoFo, the bodies had been removed and taken to the medical examiner’s office in Brewster, which serviced Red Hill as well as four other nearby towns. The ME’s office, Williams had told them, was, because of years of steep cutbacks, woefully understaffed, and there was a backlog of autopsies. The office had only one full-time doctor on staff. The part-time doctor who had been helping out had retired at the end of last year, and the office’s request for a deputy coroner had been denied.

She didn’t need to explain the importance of having an autopsy performed before the organs had completely deteriorated. Williams had followed the morgue van to Brewster to plead his case to Ben Stern, the district coroner and chief medical examiner. Williams promised he’d beg – on his knees, if necessary – to get the autopsies slated for sometime tomorrow.

Darby doubted Ray Williams would have to go to such lengths. Like Coop, the Red Hill detective had been blessed with effortless charm, someone who could get both men and women to do favours, pull strings and jump through hoops with smiles on their faces.

Darby entered the house. She put on a mask, then signed the log and moved up the stairs. Coop appeared in the bedroom doorway, his head and face covered by a hood and a respirator mask.

‘Bad news on the duct tape,’ she said to him. ‘No prints on the adhesive side. The smooth side, I don’t know yet; they’re in the Superglue Chamber.’

‘Not that surprising. We know this guy’s careful.’

‘What I did find, though, was a small piece of latex that’s marked with what looks like ink. If we can get sweat or some skin cells off it, we might have a DNA sample.’

‘Otto and I just finished using luminol. Our man didn’t use bleach to wipe down anything inside the bathroom, and he didn’t dump it down any of the drainpipes either. We took them apart and swabbed them just to be sure. Now come and take a look at this.’

She followed him to the corner of the bedroom. A square section of flooring had been removed and then taken apart and placed inside evidence bags.

‘In addition to using Mr Clean on this area, he also used bleach,’ Coop said. ‘I sprayed it with luminol and everything glowed. The hardwood is old and scuffed – it’s probably the original flooring. The poly sealant is pretty much gone, which is good news for us. The chemicals and rag or whatever he used couldn’t penetrate the crevices between the boards.’

‘You find blood?’

‘Yeah,’ Coop said. ‘A ton of it.’

I find Red Hill incredibly depressing this time of year – grey winter mornings and short afternoons where the wind hits your skin like a drill bit, keeping people off the streets and tucked inside their homes. By 4 p.m., the world is swallowed inside a pitch-black darkness.

And yet it is during this time – what I call my ‘black hole hours’ – when I feel the most alive – when the part of me that I keep hidden during the daylight is wide awake, throbbing for attention.

Just a glimpse, I tell myself as I drive. Just a glimpse, and then I’ll go home.