The Empty Chair by Jeffery Deaver

Maybe because the slovenliness suggested that his foster parents didn't really give a damn about the boy and that this neglect had contributed to his becoming a killer and a kidnapper.
    Sachs scanned the room fast and noticed that there were dozens of smudges and finger- and footprints on the windowsill. It seemed he used the window more than the front door and she wondered if they locked the children down at night.
    She turned to the wall opposite the bed and squinted. Felt a chill slide through her. "We've got ourselves a collector here, Rhyme."
    She looked over the dozen large jars – terrariums filled with colonies of insects clustered together, surrounding pools of water in the bottom of each one. Labels in sloppy handwriting identified the species: Water Boatman . . . Diving Bell Spider. A chipped magnifying glass sat on a nearby table, beside an old office chair that looked as if Garrett had retrieved it from a trash heap.
    "I know why they call him the Insect Boy," Sachs said, then told Rhyme about the jars. She shivered with revulsion as a horde of moist, tiny bugs moved en masse along the glass of one jar.
    "Ah, that's good for us."
    "Why?"
    "Because it's a rare hobby. If tennis or collecting coins turned him on, we'd have a harder time pinning him to specific locations. Now, get going on the scene." He was speaking softly in a voice that was almost cheerful. She knew he'd be imagining himself walking the grid – as he referred to the process of searching a crime scene – using her as his eyes and legs. As head of Investigation and Resources – the NYPD's forensics and crime scene unit – Lincoln Rhyme had often worked homicide crime scenes himself, usually logging more hours on the job than even junior officers. She knew that walking the grid was what he missed most about his life before the accident.
    "What's the crime scene kit like?" Rhyme asked. Jesse Corn had dug one up from the Sheriff's Department equipment room for her to use.
    Sachs opened the dusty metal attaché case. It didn't contain a tenth of the equipment of her kit in New York but at least there were the basics: tweezers, a flashlight, probes, latex gloves and evidence bags. "Crime scene lite," she said.
    "We're fish out of water on this one, Sachs."
    "I'm with you there, Rhyme." She pulled on the gloves as she looked over the room. Garrett's bedroom was what's known as a secondary crime scene – not the place where the actual crime occurred but the location where it was planned, for instance, or to which the perps fled and hid out after a crime. Rhyme had long ago taught her that these were often more valuable than the primary scenes because perps tended to be more careless in places like this, shedding gloves and clothes and leaving behind weapons and other evidence.
    She now started her search, walking a grid pattern – covering the floor in close parallel strips, the way you'd mow a lawn, foot by foot, then turning perpendicular and walking over the same territory again.
    "Talk to me, Sachs, talk to me."
    "It's a spooky place, Rhyme."
    "Spooky?" he groused. "What the hell is 'spooky'?"
    Lincoln Rhyme didn't like soft observations. He liked hard – specific – adjectives: cold, muddy, blue, green, sharp. Rhyme even complained when she commented that something was "large" or "small." ("Tell me inches or millimeters, Sachs, or don't tell me at all." Amelia Sachs searched crime scenes armed with a Glock 10, latex gloves and a Stanley contractor's tape measure.)
    She thought: Well, I feel damn spooked. Doesn't that count for anything?
    "He's got these posters up. From the Alien movies. And Starship Troopers – these big bugs attacking people. He's drawn some himself too. They're violent. The place is filthy. Junk food, a lot of books, clothes, the bugs in the jars. Not much else."
    "The clothes are dirty?"
    "Yep. Got a good one – a pair of pants, really stained. He's worn them a lot; they must have a ton of trace in them. And they all