Sometime in the spring of freshman year, when things finally settled enough to reveal what life would be like now that it had a big fat line drawn through it—before the slaughter, after—I received a letter from Mrs. Finnerman. Her handwriting appeared unstable on the page, like she’d been a passenger in a car flying down a potholed road when she wrote it. She wanted me to know that she was so sorry for what I’d had to do. She had no idea the rage and the hatred simmering in Arthur, her own child—how could she not have known, she berated herself over and over.

Mom forbade me from writing her back, but I did anyway (“Thank you. I would never blame you for what he did. I don’t hate him. Even miss him sometimes”). I folded the piece of paper in half and slipped it under her door on an afternoon I noticed her car wasn’t in the driveway. I wasn’t strong enough for a tête-à-tête just yet, and I sensed Mrs. Finnerman wasn’t either.

After I graduated college, Mrs. Finnerman sent me the occasional card, and an odd sort of relationship developed. She reached out when the news trickled down that I’d gotten engaged, and when she read an article she liked in The Women’s Magazine. She ripped out one in particular, “Does Facebook Make You Sad?” Sent it in an envelope along with an article from The New York Times, titled “The Depressive Effect of Facebook.” She circled the date on each—mine written in May 2011, the Times’s version on February 7, 2012. “You scooped the Times,” she wrote. “Brava, TifAni!” It was the cheery correspondence of old friends, and that was a mistake, because Mrs. Finnerman and I weren’t friends. This would be the first time we’d seen each other since before the shooting.

I smiled shyly. “Hi, Mrs. Finnerman.”

Mrs. Finnerman’s face wadded up like a wet paper towel. I stepped forward, unsure, and she frantically fanned her hand at me, waving off my hug. “I’m all right,” she insisted. “I’m all right.”

The coffee table in the living room was piled high with photo albums and old newspapers. The choice placement of a coffee mug altered a headline in a yellowed copy of The Philadelphia Inquirer, POLICE THINK GUNMEN DID WORK ALONE. Mrs. Finnerman picked up the cup and the word “not” reappeared, righting my fate.

“What can I get you to drink?” Mrs. Finnerman asked. I knew she drank only green tea because I’d come across her stash once, stoned and searching for a jar of Nutella.

“Yeah,” Arthur had said as I marveled at it. Green tea seemed very exotic to someone like me. Mom drank Folgers. “My mom is really anti-coffee.”

“Tea is fine,” I told her. I hate tea.

“Are you sure?” Mrs. Finnerman’s bulky glasses slid forward on her nose, and she pushed them back with her index finger, just like Arthur used to do. “I have coffee.”

“Maybe coffee then.” I laughed a little, and to my relief Mrs. Finnerman did too.

“Gentlemen?” Mrs. Finnerman addressed the crew.

“Please, Kathleen,” Aaron said. “Like I said, pretend we aren’t even here.”

For a moment I thought Mrs. Finnerman would unravel again. I held my breath, bracing, but she surprised everyone by throwing up her hands. “Like I could do that.” She laughed, wryly.

Mrs. Finnerman disappeared into the kitchen, and I heard cupboard doors clapping open and shut. “Milk and sugar?” she called.

“Just milk!” I called back.

“What’s it like being here again?” Aaron asked.

I looked around the room, at the faded fleur-de-lis wallpaper and the harp hulking in the corner. Mrs. Finnerman used to play, but now the strings peeled back like split ends in need of deep conditioner.

“Weird.” As soon as I said it, I remembered Aaron’s instructions from earlier. I should answer his questions in a complete sentence, since they would edit out his voice and what I said had to make sense on its own. “It’s very strange to be back here.”

“Here we go.” Mrs. Finnerman stepped carefully into the room, handing me a mug so misshapen it had to be handmade. I caught the engraving on the bottom, “To: Mom, Love: Arthur 2/14/95.” There was no handle, and I had to transfer the cup from hand to hand every few seconds, when the heat became too much for one side to tolerate. I took a scalding sip. “Thank you.”

Mrs. Finnerman was rooted to her spot beside the couch. We both looked at Aaron, desperate for direction.

Aaron indicated the open seat beside me. “Kathleen, why don’t you sit next to Ani on the couch?”

Mrs. Finnerman nodded her head and muttered, “Yes, yes.” She walked around the coffee table and settled into the far end of the couch. Her knees pointed at the front door, away from the kitchen. I was closer to the kitchen.

“It will help the shot if you can scooch in a little closer.” Aaron pinched his fingers together to show us what he meant.

I couldn’t look at Mrs. Finnerman as I “scooched” toward her, but I imagined she had the same polite, mortified smile on her face as I did.

“Much better,” Aaron said.

The crew waited for us to say something, but the only sound was the hush of the dishwasher running in the kitchen.

“Maybe you could go through the photo albums?” Aaron suggested. “Talk about Arthur?”

“I’d love to see,” I tried.

As though programmed by the two of us, Mrs. Finnerman leaned forward robotically and picked up a white photo album. She swept away a whisper-light dust bunny. It caught on the edge of her pinkie and reattached itself to the laminated cover.

The album creaked open on her lap, and Mrs. Finnerman blinked down at Arthur, maybe three years old. He was mid-scream, clutching an empty ice cream cone. “We were in Avalon here,” Mrs. Finnerman murmured. “A seagull swooped down”—she swished her hand through the air—“knocked the whole scoop right off the cone.”

I smiled. “We used to go through ice cream by the carton here.”

“I know how he did it.” Mrs. Finnerman flipped the page, forcefully. “But not you. Tiny little thing that you are.” There was something menacing in her voice. I didn’t know what else to do but pretend I didn’t notice.

“Oh, this.” Mrs. Finnerman brought her chin to her chest and sighed longingly at a picture of Arthur curled around a yellow Lab, his face burrowed in her buttery fur. Mrs. Finnerman tapped the dog’s snout. “This was Cassie.” Her smile was all lip. “Arthur loved her. She slept in his bed every single night.”

The cameraman moved behind us, his long lens closing in on the picture.

I reached out to hold the page down, to deflect the glare obscuring my view, but Mrs. Finnerman brought the album to her chest and tucked her chin over its leather ledge. A tear rolled, clung to the edge of her chin. “He sobbed when she died. Sobbed. So he couldn’t be what they say he is. He had emotions.”

What they say he is. A psychopath. Incapable of experiencing true human emotions, only mimicking those he observed in others: remorse, grief, compassion.

A lot of time and energy went into dismantling the dynamic between Arthur and Ben, identifying the leader of the pack. Understanding their motives would bring closure to the community, and the information could prevent a recurrence at another school. The country’s most renowned psychologists examined the evidence collected in the aftermath of the attack on Bradley—Ben’s and Arthur’s journals, their academic records, interviews with neighbors and friends of the family—and every single one arrived at the same conclusion: Arthur called it.

I arranged my face to signal sympathy, like Arthur had done for me so many times. “Do you know what I remember about him?”

Mrs. Finnerman plucked a tissue out of a box on the coffee table. Her face went maroon as she blew into it. She folded the tissue in half and wiped her nose. “What’s that?”