“Did we talk to the Uber driver?” Abe asked.

“Yeah, but she doesn’t remember a thing,” Merle said. “Dropped the kid off and moved on to her next ticket.”

Merle looked to Remy, who clicked forward to a shot of Harrington’s station wagon, parked at the middle school.

“Next moment we’re aware of,” Remy said. “Harrington exits his car.” She pointed at the screen, where an overhead map of the campus was projected. A red X appeared over the parking lot, and my partner walked over. Touched the TV.

“He parked here,” she said. “He’s now on campus for three minutes. It’s 1:47.”

“A mom who volunteers at the school passed Harrington,” Merle said, and Remy pointed at a second X.

“He crossed the parking lot from here to there.” She motioned from west to east.

“How’s Harrington acting?” I asked.

“From Mom’s memory—normal,” Merle said. He glanced down at a jelly stain on his shirtsleeve, clearly not sure when it had left the donut and arrived on his cuff. “Mom didn’t think anything of it ’til his picture hit the news,” Merle continued.

“How was he concealing the weapon?” Abe asked.

This was a good question. A .38 Special was a revolver with a bulky profile. Tough to hide.

“The mom saw no weapon,” Merle said. “So we reckon it was shoved in his waistband or at his back. Harrington was wearing an untucked flannel.”

I looked at Remy and Merle’s diagram. Harrington had parked fairly close to the art class and was moving directly toward it. “Looks like he knows where he’s going.”

“Merle and I thought the same thing,” Remy said without adding another word.

This was the approach I’d taught her. When you’re building a timeline, your job is to itemize the facts. It’s everyone else’s job to theorize.

“When’s he spotted next?” the chief asked, moving things along.

“That’s where accounts vary depending on who you talk to,” Remy said. “But let’s walk through the most likely scenario.”

“Around this time, a class ends if you’re in seventh or eighth grade,” Merle said. “It’s 1:50 p.m. The bell rings. Students move around. Harrington’s now been on campus for six minutes, and no gun has been pulled, from what we know. He’s just another adult walking.”

Remy clicked on her computer, and a picture of a room came up. “This is a storage room attached to the art room,” she said. “It’s got a kiln. Some sort of small printing press. A cordless sander.”

“Minor power tools,” Merle said. “Stuff the kids need adult supervision to work with.”

Remy clicked again, and beside the same picture appeared a hand-drawn overhead diagram, showing two doors entering this storage area.

“There’s two ways into this storage room,” she said. “One is through an outdoor courtyard not far from the teacher’s lounge. That’s a locked door that only teachers have access to. The other is through the art room itself.”

We all nodded, waiting for Remy and Merle to explain why their focus had shifted to this storage area.