Where was I when it happened? Like a lot of kids, I was in a classroom watching the clock with its slow, indifferent hands. It was almost time for lunch, and no one was paying attention to Mr. Maynard, who was trying to teach us about fault lines.

I’ve thought about it thousands of times, how, exactly one year ago, my brother stood on the concrete outside of the library while I wrote in my science notebook, “Fault line: not typically formed by a single fracture but by a series of fractures.” I was in the middle of copying the diagram of the San Andreas Fault that Mr. Maynard had drawn on the board when I heard the gunshots.

From the third floor, they sounded like popcorn. My best friend Carly, who was on the second floor in history class, thought they were firecrackers set off by a prankster so that we’d have to have a fire drill, some boy who had a test or was really hungry or wanted to go get high behind the gym. The real thing, no one could have imagined. Ninth-grade science class—Earth Science, they call it: that’s where I was when Paul Martin, a senior at Cauthen High School in Grenfell, Virginia, killed four human beings.

This is where my story begins, but mine is not the story you hear on the news or read in the papers. Mine is a sister’s story.

Paul was my brother, my only sibling. He was the one who had shared his ice cream with me, my backseat brother who had played tic-tac-toe with me on the long drives to visit our aunts and uncles, my brother who had held me in his three-year-old arms the day I was born. Please don’t take this the wrong way, but if I try really, really hard, I can kind of, ever-so-slightly, understand why he would want to shoot his ex-girlfriend, but the janitor? What need could he have possibly fulfilled by aiming a gun at Mr. Dan? Mr. Dan was nice to everybody, even if they weren’t nice back. Mr. Dan drove Paul home once from school when my mom forgot to pick him up after football practice.

And Miss Albright, the AP English teacher. Paul was not an AP English student, but his ex-girlfriend Jessica Beam was, and when Miss Albright dove to push her out of the way, Jessica hit her temple on the corner of a table. Now she has a scar from her hairline to her right eye, but at least she’s alive, unlike Miss Albright. The Beams go to the same church as my family, and her parents and my parents were friends before this. My mom and dad carry the guilt of ten thousand parents, but I’m the one, the only one in the whole world, who could have stopped it from happening.

A day before the shooting, a Thursday, late afternoon, Paul and Jessica were down at the creek behind our house. It was late February, and because the leaves weren’t yet on the trees, I could see them from the attic window. The attic is where I go when I can’t understand my life. I started coming here four years ago during my Anne Frank phase. Anyway, you don’t want to hear about that. So, back to the creek.

Jessica was breaking up with him, that much was clear. She handed something to him about the size of a photograph. Then Paul’s face split wide open, and he burst into tears. And “burst” is the right word for it. I had never seen my brother cry. Even when he broke his arm back when he was nine, he didn’t. Even when our grandfather died, whom we saw every Sunday of our lives.

Jessica just stood there; she didn’t reach out to hug him or touch him. When he tried to hand the thing back, she wouldn’t take it. She kept shaking her head, and Paul got angry, stuffing the thing in his back pocket before he grabbed her by the shoulders and shook her, causing her to lose her balance. She fell backwards into brittle leaves, left over from another season. And then Paul picked up the rock. For a few seconds, he tossed it up and down in his hands. I thought he was going to throw it at Jessica. She must have thought that, too, because she scrambled to her feet and took off running, up through the backyard and down the driveway where her car was parked. Paul watched until she drove away, his shoulders hunched like a monster’s.

That should have been the end of it. I wish every single second of the day and night that that had been the end of it. Because what Paul did next was this: he raised the rock high with both hands and brought it down on top of his head, full contact. I don’t know how long he stayed crumpled on the ground, palms pressed to his scalp. I wanted to go to him—in fact, when I turned from the window to do just that, Paul rolled himself up from the leaves and staggered back to the house.

I was waiting for him outside of his room. There was blood in his hair. “Let me see,” I said, but he shook me off.

“I’ll be fine,” he said. “Don’t tell Mom.”

I didn’t say anything. I tried to shift my face close to his, but he kept turning away. His eyes were filmy.

“I mean it,” he said. “Don’t tell Mom. Or Dad.”

“But you might need stitches.”

“I don’t need stitches.”

But he did.

I had grown used to standing on the other side of Paul’s closed door, but this time, he locked it. I knocked and waited, knocked and waited. Then I went back to the attic and stared out the window until the light folded into the ridge and the trees along the creek lined themselves up, silent and black.

My last promise to my brother, I am keeping: I have not told Mom or Dad. If I told Mom and Dad all that I know, it will be so much worse. Secrets are, in their way, more powerful than guns. Secrets can make you feel like an alien even after they are no longer secret. With secrets, countless lives can be turned upside down: you can have an entire city of fathers, mothers, sisters, brothers, aunts and uncles, dogs and cats, and grandparents walking around on their heads, their feet (and paws) dangling over them, completely useless.

Paul had stolen my grandmother’s gun, the one she bought to protect herself after my grandfather died. How did he even know how to load a gun? Is it something that boys know instinctively, the same way they know how not to throw like a girl? My grandmother feels responsible, but my dad tells her over and over that she’s not. He tells me the same thing, mostly during our therapy sessions. Mom and Dad continue to go to therapy every week, and every other week, I go with them. I assure them that I am fine, just sad at times, and that they don’t need to worry about me. I’m not wired like Paul. I’m not wired at all. I am cool, cool as a cucumber. The path of least resistance is the one I follow now.

I didn’t want to go back to school after the funerals, and didn’t for a few weeks, until just before spring break. More than once in the middle of the night, I packed a suitcase so I could run away, but in the morning, I unpacked it again. I had friends besides Carly, but how would they feel now? Guilt by association: the killer’s sister. I dreamed that my English teacher made me come to the front of the room and dump out the contents of my backpack, which was full of heavy rocks and bloody bullets. I begged my mom and dad to send me to Alaska or Siberia, anywhere but Grenfell, and when I mentioned going to live with my aunt for a while, my mom started crying, so I didn’t bring it up again. Eventually Mr. Burton, the principal, called my house and asked softly to speak with one of my parents.

They had decided to close the school library for the rest of the year, but Mr. Burton told my mom that he thought I might like to go in there by myself on a weekend before my official re-entry. I didn’t want to make him feel any worse than he already did, so I went. On a Sunday afternoon, my mom dropped me off at the front entrance of school where Mr. Burton was waiting. He waved to Mom as she pulled away. “She’s just going to the grocery store,” I told him so he wouldn’t think he’d be stuck with me for hours.

I followed Mr. Burton down the empty hall, our footsteps doing the talking for us. His were saying, “This should not be my job, this should not be.” Mine were saying, “Paul, I hate you, I hate you.” When we got to the library, Mr. Burton took a single key out of his pocket, unlocked the wide glass doors, and stepped inside to turn on the lights, which began to buzz. He held one of the doors open for me. “Take your time,” he said.

I stepped inside to a place that had, up until then, been a sanctuary. The fact that I had never been in the Cauthen High School Library on a Sunday afternoon made it surreal enough, but the fact that there wasn’t a speck of blood on the carpet or walls made me feel like I had lost my legs. Like a torso hanging in the dark between my dreams and my life. The library no longer smelled like musty books. It smelled plastic and fake, like Band-aids.

The last daylight was coming in through the tall windows, and because they faced west, the sun revealed every particle of dust. I don’t know how long I watched the motes rise and fall. Mr. Burton had left me alone; now it was just me and the books, silent guardians of the truth. Standing there by the checkout desk, I started to realize the full extent of the damage—mine, not Paul’s. Paul was dead. After he killed Miss Albright and Molly Mahan, he put the gun to his head and pulled the trigger, and that was the end of his story.

Witnesses say that Paul forced Jessica’s best friend Molly to read a poem out loud from a book he grabbed off the library shelf before he shot Molly in the stomach. Paul wasn’t a reader—I was the reader—but he knew things that I didn’t. Even before the shooting, something had changed. He understood the language of the body, a language that I did not yet share.

Paul did not choose the poem “The Touch” at random even though that had been the impression. If you read it, you will see it for yourself—the locked-up hand aching for something to love that will love it back; the father and mother who had become the machine; the sister at school crying her lemonade tears. And the last stanza:

Then all this became history.
Your hand found mine.
Life rushed to my fingers like a blood clot.
Oh, my carpenter,
the fingers are rebuilt.
They dance with yours.
They dance in the attic and in Vienna.
My hand is alive all over America.
Not even death will stop it,
death shedding her blood.
Nothing will stop it, for this is the kingdom
and the kingdom come.

Paul arranged Jessica and the other students in the library in a half-moon around Molly as she choked out the words of a dead poet. The poem wasn’t from a library book, as was naturally assumed. It was from my own room, my own shelf. I had put my collection of Anne Sexton’s poems in Paul’s backpack the night before, marking “The Touch” with a pink Post-it note.

I had meant the poem as a comfort—as makeshift, inadequate stitches for what had happened by the creek. And now all the books on all the shelves in all the libraries of the world were soldiers standing at attention. That is what I was thinking when Mr. Burton touched me on the shoulder and said that my mom had returned from the grocery store. The old me wanted to stay in the library through the night, through the spring, through the rest of my life with the rising and falling motes because the new me understood that the old me was dust.

On the drive home, my mom told me that Jessica Beam planned to go off to boarding school after spring break, and I was jealous. For me, boarding school was not an option; it would have been just one more overwhelming possibility for my parents to consider. Our heads still hang low with maybes and what ifs. Like what if I tell my parents what I saw from the attic. Like what if I tell them what I learned afterwards.

I had been right, in a way: what Jessica handed to Paul was a sort of photograph. The night after the shooting, I went into Paul’s room, which for once wasn’t locked. The jeans he’d worn the day before were in his laundry basket, the black-and-white image of an ultrasound crushed in the back pocket. The one person I did tell was Carly, who thinks that Jessica had the abortion before the shootings, but if that’s the case, then why would she show him the image of the ultrasound? Maybe Paul didn’t even know Jessica was pregnant until that moment. As it is with so many things, I have to wonder.

The exact moment that Paul shot Mr. Dan in the back in the long hall outside of the library will never be determined. I told my therapist that it had to have been a mistake rather than some sick kind of target practice. I choose to believe that on that day, neither Paul nor Mr. Dan knew who the other one was. On that day, Paul didn’t even know himself: he had suffered a chain of fractures; he had cracked right down the middle. Now any time a teacher says we are going to the library, the kids in class examine me with microscope eyes.