“Fine, I’m getting dressed.”

This is not the truth, either. I am actually wearing my underwear and a T-shirt right now.

“Okay,” she says. “Well, give a holler when you’re done.”

I wait until her footsteps fade down the hall, and then I remove the glass from beneath the fish tank. Sure enough, there are several prints. I dust them with a dual-use powder, which has contrast on both white and black surfaces. Then I dust the prints on the second item, too.

I photograph them at close range with the digital camera I got for Christmas two years ago and load the images into my computer. It’s always a good idea to photograph your latent prints prior to lifting them, just in case you destroy them during the process. Later, in Adobe Photoshop, I can invert the colors of the ridges and resize the prints. I can begin an analysis.

I carefully tape over the print to preserve it, intending to hide what I took away from her house in a place where no one will ever find it.

My mother, by then, is tired of waiting. She opens the door. “Jacob, put on a pair of pants!”

She holds her hand over her eyes but enters my bedroom all the same.

“No one told you to come in,” I say.

She sniffs. “You’ve been using Krazy Glue again, haven’t you? I told you I don’t want you fuming while you’re in the room-that can’t be good for you.” She pauses. “Then again, if you’re fuming, you must be feeling better.”

I don’t say anything.

“Is that your cocoa in there?”

“Yes,” I say.

She shakes her head. “Come on downstairs,” my mother sighs. “I’ll make you a fresh cup.”

Here are some facts about forensics:

1. Forensics is defined as the scientific methods and techniques used in connection with the detection of crime.

2. The word forensic comes from the Latin forensis, which means “before the forum.” In Roman times, a criminal charge was presented in front of a public group in the forum. The accused and the victim would give testimony, and the one who had the best argument would win.

3. The first written account of forensics to solve cases was during the Song Dynasty in China in 1248. After a person was killed with a sickle, an investigator told everyone to bring their sickles to a specified location, and when the flies were drawn to one by the smell of blood, the murderer confessed.

4. The earliest incidence of fingerprint use to determine identity was in the seventh century, when a debtor’s fingerprints were attached to a bill, as proof of the debt for the lender.

5. Forensic science is a lot easier to perform when you aren’t personally involved.

The tips of your fingers, the palms of your hands, and the soles of your feet aren’t smooth. They are friction-ridged skin, series of lines with contours and shapes, like a topographical map. Along those lines are sweat pores, and if they become contaminated with sweat, ink, blood, or dirt, they’ll leave a reproduction of those lines on the object that’s been touched. Or, in less fancy terms, a fingerprint.

If the print can be seen, it can be photographed. If it can be photographed, it can be preserved and compared to a known sample. It’s an art as much as it’s a science: since I don’t have an AFIS terminal in my house to scan the latent print and spit out fifty candidates with matching similarities, I have to rely on the naked eye. The goal is to find ten to twelve similarities between the known sample and the latent print-that’s what most examiners would conclude to be a match.

On my computer screen, I set images of the two prints. I place my cursor on the core, the centermost part of the print. I mark a delta-a small triangular formation to the left of the core. I note ending ridges and bifurcations and a circular whorl. A bifurcation, then two ridges, then another bifurcation downward.

Just like I assumed: This is a match.

That makes me feel like I am going to throw up, but I swallow and force myself to do what needs to be done.

Like yesterday.

Shaking my head clear, I take a small Tupperware container that I’ve filched from the kitchen and place the evidence inside. Then I rummage around in my closet until I find Jemima Puddle-Duck. She’s a stuffed animal that I used to sleep with when I was a kid, and because she is white, she is up on a shelf above the rest of my clothes that have actual pigmentation. I place her facedown in my lap and, using a box cutter, make an incision in the place where she might have had a heart.

The Tupperware has to be jammed inside, and it makes Jemima look like she has an unsightly rib cage, but it works. I suture her with the same thread I used last week to fix a hole in my sock. I’m not very good at it-I stick myself nearly every stitch-but I get the job done.

Then I take out a notebook and start writing.

When I am done, I lie down on my bed. I wish I were at school. It’s harder, when I’m not working at something.

“I shot the sheriff,” I whisper. “But I swear it was in self-defense.”

I’ve often thought about how a person could commit the perfect crime.

Everyone always talks about the proverbial icicle-stab someone and the murder weapon will melt-but it’s a long shot (a) that you will be able to grip that icicle long enough to inflict a wound and (b) that it won’t break off when it hits the skin before puncturing it. Mescaline sprinkled over someone’s salad would be subtler-the brown powder would be virtually indistinguishable mixed with vinaigrette, and you wouldn’t taste the bitter flavor, especially if there was chicory or arugula in the mix. But what if you only made your victim have a bad trip instead of die, and plus, where would you get your stash? You could take someone sailing and shove him overboard, preferably after getting him drunk, and say he fell accidentally-but then, you would need to have a boat. A mix of Vicodin and alcohol would slow the heart excessively, but your victim would have to pretty much be a party animal for a detective to not find that suspicious. I’ve heard of people who try to burn down a house after committing murder, but that never really works. The arson inspectors can trace where the fire started. Plus, a body has to be charred beyond recognition-and dental work-to not point a finger back at you. I wouldn’t recommend anything that leaves blood, either. It’s messy; you’ll need lots of bleach to clean it, and there’s bound to still be a drop left behind.

The conundrum of the perfect crime is complicated, because getting away with murder has very little to do with the mechanism of the killing and everything to do with what you do before and after. The only way to really cover a crime is to not tell a soul. Not your wife, not your mother, not your priest. And, of course, you have to have killed the right kind of person-someone who isn’t going to be looked for. Someone who nobody wants to see again.

Once, a girl came up to me in the cafeteria and asked me if I wanted to go to Jesus Camp. You will be saved, she told me, and man, I was tempted. I mean, it’s been pretty clear to me for a while that I’m going to hell, because of all the secret thoughts I’m not supposed to have about Jacob.

You always read these books about kids who have autistic siblings and who are constantly looking out for them, who love them to death, who do a better job defusing their tantrums than the adults. Well, I’m not one of those people. Sure, when Jacob used to wander off I’d feel sick in the pit of my stomach, but it wasn’t because I was worried about him. It was because I had to be an awful brother to be thinking what I was: Maybe he’ll never be found, and I can get on with my life.

I used to have dreams that my brother was normal. You know, that we could fight about ordinary things, like whose turn it was to control the television remote, or who got to ride shotgun in the car. But I was never allowed to fight with Jacob. Not when I’d forget to lock my bedroom door and he came in and stole my CDs for some forensics project; not when we were little and he’d walk around the table at my birthday party, eating cake off the plates of my friends. My mother said it was a house rule, and she explained it like this: Jacob’s different from the rest of us. Gee, you think? And by the way, since when does being different net you a free pass in life?