About halfway to the lane, Annie saw the plastic retaining frames around faint imprints in the mud, each with a ruler lying next to it. “Luckily, the ground was just muddy enough in places,” Stefan said. “Probably protected by the trees. Anyway, we got reasonably fresh shoe impressions, but they could be anybody’s.”
“How many?”
“Just the one person, by the looks of it.”
“Did the firefighters use this path?”
Stefan pointed. “No, down there. This is the path you’d take from the lay-by. They parked farther down, closer to the canal. This part of the woods is riddled with paths. I gather it’s a popular spot in summer.”
Annie looked down at the markings. “So they could be our man’s?”
“Yes, but don’t get your hopes up. Anyway, they’ve all been carefully photographed, and casts have been made. They’re drying out right now, but tomorrow we’ll run them through SICAR.”
SICAR was an acronym for Shoeprint Image Capture and Retrieval, which combines a number of scanned databases to match footwear files with specimens, primarily the “Sole-mate” database of over three hundred common brands of shoes and two thousand different sole patterns. Stefan’s expert would have sprayed the muddy impression with shellac or acrylic lacquer, then he would have made a cast in dental stone. Back at headquarters, he would enter the details of the shoe impression on the computer, coding by common patterns such as bars, polygons and zigzags, and by manufacturers’ logos, if any were present. From these reference databases, they could find out what type and brand of shoe caused the imprint, and they could also search the crime and suspect databases to see if it matched the shoe of a person taken into custody, or a footprint left at a previous crime scene.
Of course, what everyone really hoped for was something more than just class characteristics, some sort of unique markings, the kind that come from wear and tear, a nice drawing pin embedded in the sole, for example, something that could be matched with a specific shoe. Then, once you have your suspect and his shoe, you have solid evidence that links him to the scene.
They got to the lay-by, beside which the police mobile unit was parked, completely blocking the lane. It didn’t matter much, though, as the track was hardly ever used and it led only toward a narrow bridge over the canal about two miles west. Anyone wanting to get there was advised to take the next turning by a diversion sign posted at the junction of the lane and the B-road half a mile north.
Annie noticed more retaining frames, measures and markers on the lay-by itself.
“Impressive,” she said. “You have been busy.”
“We’ll see,” said Stefan. “Trying to process a crime scene like this is like peeling the layers off the onion, and you don’t know which layer is the important one.” He pointed to one of the imprints. “Here we’ve got parallel tire tracks,” he said. “And that should be enough to tell us who the manufacturer was. From these we can also get the track width and wheelbase measurements, which might even help us identify the make of the car. If there are a number of individual characteristics present in the tire impressions, which may be the case, then we should be able to match them to the specific tire, and vehicle, too.”
“If and when we find it,” said Annie.
“Naturally. We’ve also collected soil samples from the entire area. No rare wildflowers at this time of year, of course, but there are some unique mineral features, and they should also help us tie in the shoes and tire to the scene, should we find them.”
“And should they still be dirty.”
Stefan narrowed his eyes. “Trace evidence can be microscopic sometimes. You ought to know that. You’d be surprised how little we can work with.”
“I’m sorry,” said Annie. “I don’t mean to be negative. It’s just… I have a feeling we’re not dealing with an amateur here.”
“And we’re not amateurs, either. Besides, we don’t know what we’re dealing with here yet.”
“True enough,” Annie agreed. “I’m just suggesting that he’ll have done his best to cover his tracks, and the longer it takes us to find him…”
“The more tracks he’ll manage to cover. Okay, I’ll grant you that. But it’ll take more than a car wash and a good polishing to get rid of every atom of soil he might have picked up here. Besides, don’t forget, we’ve got the tire impression to go on. There’s an oil stain, too, by the looks of it.” He pointed to another protected area on the lay-by. “We’ll have that back for analysis by the end of the day. It’s certainly beginning to look as if someone parked here recently, and if it wasn’t you or the fire brigade…”
Annie knew that it was neither she nor Banks. They had been concerned to preserve as much of the scene as they could when they arrived, almost by instinct, so they had left their cars farther up the lane and made their way through the woods without benefit of using a marked path. All in all, then, things were looking promising. Even if the evidence that Stefan and his team painstakingly collected didn’t lead them directly to the arsonist, it would come in useful in court when they did find him.
“Any chance it was a Jeep Cherokee?” Annie asked, remembering what Banks had told her Mark said he’d seen. “Or something similar?”
Stefan blinked. “Know something I don’t?”
“Just that something resembling a Jeep Cherokee has been reported seen in the area. Not last night, but recently.”
Stefan looked down at the tire tracks. “Well,” he said, “it’s something to go on. We can certainly compare wheelbase and track width. Anyway,” Stefan said, opening the door of the mobile unit with a flourish, “it’s not exactly the Ritz, but the heater works. How about coming in for a cuppa?”
Annie smiled, her body leaning toward the source of heat the way a sunflower leans toward the sun. “You must be a mind reader,” she said, and followed him in.
By the time Banks and Frances Aspern got to Western Area Headquarters after Mrs. Aspern’s positive identification of Christine at the mortuary of Eastvale General Infirmary, Annie had already left to talk to the SOCOs at the canal. Banks arranged for a uniformed constable to drive Mrs. Aspern back home, and he had just settled down to review the findings so far, with Gil Evans’s Jimi Hendrix orchestrations playing quietly in the background, when Geoff Hamilton appeared at his office door. Banks invited him in and Hamilton sat down, glancing around.
“Cozy,” he said.
“It’ll do,” said Banks. “Tea? Coffee?”
“Coffee, if you’ve got some. Black, plenty of sugar.”
“I’ll ring down.” Banks ordered two black coffees. “Anything new?”
“I’ve just come from the lab,” Hamilton said. “We carried out gas chromatograph tests this afternoon.”
“And?”
Hamilton took two sheets of paper and a videotape from his briefcase and laid them out on Banks’s desk. The sheets of paper looked like graphs, with peaks and valleys. “As you know,” he said, looking at Banks, “I took debris samples from a number of places, especially on boat one, Tom’s boat, the main seat of the fire. I don’t know how much you know about it,” he went on, “but gas chromatography is a relatively simple and quick process. In this case, we put the debris in large cans, heated them and used a syringe to draw off the headspace, the gases given off, and we then injected that into the chromatograph. This” – he pointed to the left graph – “is the chromatogram we got from the point of origin.” He then pointed to the graph beside it, which, to Banks, looked almost identical. Both showed a series of low to medium peaks with one enormous spike in the middle. “And this is the chromatographic representation of turpentine.”