I thought of the teacher who’d died, and I texted Remy to find out if Harrington and Tanner knew each other. The answer came back fast:

No evidence to show that. And no one in the school recognizes Harrington.

After working my way through the grouping of boxes on the right, I inspected the left dozen, closest to the door. Each had the same initials on the box tops: G.U.

Those boxes were all empty. No manila file folders in them. No papers at all.

I walked over to the Rolodex and looked through the G’s.

An index card read G.U. in the upper corner, written in red Sharpie. But there were no other markings on the card, other than a chicken scratch of two paw marks.

I glanced at all the file boxes, now spread throughout the room. Among all the investigative pieces Harrington had done, I’d found no articles about corruption at any school board. Nothing about science education to tie him to the dead science teacher.

I heard a noise and stepped into the yard.

The dawn smelled like night-blooming jasmine, and the cobalt sky showed pops of yellow. It always shocks me how much time passes at a crime scene. Now, at almost six a.m., a familiar face was coming toward me.

Mandelle Clearson was an Atlanta PD detective who I knew from two previous cases.

In the first one, I’d helped him find a murder suspect who was hiding in Mason Falls, thinking the area was too rural for APD to chase him. Then earlier this spring, Mandelle had returned the favor and helped me with a case down in Little Five Points, his home precinct.

“Mandelle,” I said as he approached. He was nearabout fifty and my build, with salt-and-pepper hair. “What are you doing here?”

Mandelle explained that he was one of a dozen detectives in Atlanta who was a liaison for the ATF, the Bureau of Alcohol, Tobacco, Firearms and Explosives, a division of the Justice Department.

“When a high-profile case involving a gun comes up,” he said, “they cover my O.T. and send me around the state.”

“So you heard the shooting was in Mason Falls?” I asked.

“I did.” Mandelle nodded. “Figured you’d appreciate a friendly doing the gun trace.”

“Absolutely,” I said.

Mandelle told me he’d just come from my precinct, where he’d inspected the .38 that Harrington had used to kill Leaf Tanner. Now Chief Senza had sent him here, to go through the rest of the reporter’s armory.

I showed Mandelle the gun case, and he explained that once he had the serial numbers, he’d work with ATF staff in Martinsburg, West Virginia. They’d liaise with the gun manufacturer, who’d supply the store or distributor who peddled the weapon.

“From there, everything is old-school,” Mandelle said. “On a piece of paper in the gun store. The 4473.”

“What’s the timing on a trace like that?” I asked. “Start to finish?”

“Normally two weeks,” Mandelle said, laying the guns atop the white banker’s boxes as he spoke. “But in a school shooting, we’ll have results back in twenty-four hours.”