“Who shoots like that?” Sampson said. “I mean, every time?”

“Someone with serious weapons training.”

“And a sheet fetish.”

Hanson squinted. “So you think he shoots them, then throws the sheets over them?”

“No bullet holes in the fabric,” I said.

“Oh, right. But why the eyes?”

“We don’t get it either,” I said. “But if I were a young man, I’d think twice about going for an early-morning run around DC until this guy is caught.”

Sampson said, “What direction do we think the shooter came from?”

Hanson gestured to a light line in the high damp grass. “Not enough for footprints, though. He was careful to stay on the grass itself.”

I thought about that. “So maybe he’s more than just trained. Maybe he’s a hunter. Or a professional killer.”

CHAPTER 17

UP OLSON STREET SEVENTY-FIVEyards from the murder scene, Ali Cross crouched in the shadows thrown by two of the larger trees abutting the middle-school grounds and watched his father, Sampson, and police officers he didn’t know gathered around the latest victim in the Dead Hours homicides.

From this angle, he could barely see the top of the sheet, so he turned his attention to the crowd of twenty-five or thirty people who were standing across the street. With his birthday money, Ali had bought a nifty little telescopic lens that magnetically attached to the lens of his phone camera and allowed him to get detailed close-ups. He aimed the camera at the crowd. He’d heard his dad say over the years that some killers, especially serial killers, liked to slip in among the lookie-loos and watch the police reactions.

But the people he was recording on his camera werewomen with children, a handful of teenage boys, and two old men, one of them wearing one of those flat Irish caps. He was bent-backed and leaning on a cane, shaking his shaggy silver hair and full beard at something the other old man was saying.

The first old guy started coughing and hacking; he waved dismissively and limped off out of Ali’s sight.

Once Ali felt like he’d gotten everyone in the crowd on video, he turned the camera to the police and his dad.

Ali was by nature an inquisitive kid. He often became intensely interested in a particular subject — astronomy, say — and focused on it obsessively for five or six weeks, after which he’d turn to the next new thing that struck his fancy. One of the only subjects he’d never lost interest in was his father’s and Bree’s work. And Sampson’s too. Ali loved to hang around and listen to them talk shop when they thought he was absorbed in a computer game or a Netflix show.

Their world, finding criminals and putting them in jail, never ceased to fire his imagination, so Ali watched closely as Sampson and a female detective began taping off a long narrow area inside the already taped-off crime scene, from the body out past the soccer goals and close to the low chain-link fence that separated the schoolyard from the sidewalk.

His father walked slowly around the perimeter, head down, studying something in the grass.

What is he looking at? Or for?Then Ali got it.A path to the body from the street. They think the killer shot from the street.

Isn’t that kind of far for a pistol? Itwasa pistol, wasn’t it?

Ali remembered hearing Sampson and his dad talking about one of the earlier cases, and he was sure they’d said the bullets were nine-millimeters. He’d looked them up and saw that mostguns of that caliber were pistols, although a few were machine guns that the FBI SWAT teams used.

Two people in full hazmat suits exited a medical examiner’s van carrying a stretcher. On a whim, Ali climbed the closest tree and got high enough to take pictures of the sheeted body as it was loaded into a black bag. When they lifted the body onto the stretcher, he climbed back down, brushed the bark off his clothes, and checked the time.

He’d been gone from home more than an hour and a half. But his attention was caught by the police officers, who were moving into position under his dad’s direction.

They’re beginning a grid search,Ali thought, and he grinned.God, I love this —

His father was walking his way. Ali ducked down and scooted off, heading north toward the school. He didn’t stop or look back until he was beyond the building and unable to see his father or the crime scene. He slowed, his heart pounding.

OMG! Dad would strangle me if he saw me here!

Ali called for an Uber, feeling the thrill of getting away with something and enjoying every second.

CHAPTER 18

CAPTAIN DAVIS SPENT THEmorning as he always did after one of these infrequent blackouts: vowing never to drink again, wondering when the trembling in his hands was going to stop, and praying to God he had not hurt someone while he was hammered to oblivion.