“I know what you are thinking,” Felton said. “What about the sound? There is a possible explanation. Guys, let’s roll him back over.”

Bosch stood up and stepped out of the way while Felton and one of his assistants turned the body over. Bosch glanced at Walling and for a moment their eyes locked, until she looked back down at the body.

Turning the body had exposed the bullet entry wounds in the back of the head. The victim’s black hair was matted with blood. The back of his white shirt was spattered with a fine spray of a brown substance that immediately drew Bosch’s attention. He had been to too many crime scenes to remember or count. He didn’t think that was blood on the dead man’s shirt.

“That’s not blood, is it?”

“No, it’s not,” Felton said. “I think we’ll find out from the lab that it’s good old Coca-Cola syrup. The residue you might find in the bottom of an empty bottle or can.”

Before Bosch could respond Walling did.

“An improvised silencer to dampen the sound of the shots,” she said. “You tape an empty plastic liter Coke bottle to the muzzle of the weapon and the sound of the shot is significantly reduced as sound waves are projected into the bottle rather than the open air. If the bottle had a residue of Coke in it, the liquid would be spattered onto the target of the shot.”

Felton looked at Bosch and nodded approvingly.

“Where’d you get her, Harry? She’s a keeper.”

Bosch looked at Walling. He, too, was impressed.

“Internet,” she said.

Bosch nodded though he didn’t believe her.

“And there is one other thing you should note,” Felton said, drawing attention back to the body.

Bosch stooped down again. Felton reached across the body to point at the hand on Bosch’s side.

“We have one of these on each hand.”

He was pointing to a red plastic ring on the middle finger. Bosch looked at it and then checked the other hand. There was a matching red ring. On the inside of each hand the ring had a white facing that looked like some sort of tape.

“What are they?” Bosch asked.

“I don’t know yet,” Felton said. “But I think-”

“I do,” Walling said.

Bosch looked up at her. He nodded. Of course she knew.

“They’re called TLD rings,” Walling said. “Stands for thermal luminescent dosimetry. It’s an early-warning device. It’s a ring that reads radiation exposure.”

The news brought an eerie silence to the gathering. Until Walling continued.

“And I’ll give you a tip,” she said. “When they are turned inward like that, with the TLD screen on the inside of the hand, that usually means the wearer directly handles radioactive materials.”

Bosch stood up.

“Okay, everybody,” he ordered, “back away from the body. Everybody just back away.”

The crime scene techs, the coroner’s people and Bosch all started moving away from the body. But Walling didn’t move. She raised her hands like she was calling for a congregation’s attention in church.

“Hold on, hold on,” she said. “Nobody has to back away. It’s cool, it’s cool. It’s safe.”

Everybody paused but nobody moved back to their original positions.

“If there was an exposure threat here, then the TLD screens on the rings would be black,” she said. “That’s the early warning. But they haven’t turned black, so we’re all safe. Additionally, I have this.”

She pulled back her jacket to reveal a small black box clipped to her belt like a pager.

“Radiation monitor,” she explained. “If we had a problem, believe me, this thing would be screaming bloody murder and I’d be running at the front of the pack. But we don’t. Everything is cool here, okay?”

The people at the crime scene hesitantly started to return to their positions. Harry Bosch moved in close to Walling and took her by an elbow.

“Can we talk over here for a minute?”

They moved out of the clearing toward the curb at Mulholland. Bosch felt things shifting but tried not to show it. He was agitated. He didn’t want to lose control of the crime scene, and this sort of information threatened to do just that.

“What are you doing here, Rachel?” he asked. “What’s going on?”

“Just like you, I got a call in the middle of the night. I was told to roll out.”

“That tells me nothing.”

“I assure you that I am here to help.”

“Then start by telling me exactly what you are doing here and who sent you out. That would help me a lot.”

Walling looked around and then back at Bosch. She pointed out beyond the yellow tape.

“Can we?”

Bosch held out his hand, telling her to lead the way. They went under the tape and out into the street. When he judged that they were out of earshot of everyone else at the crime scene, Bosch stopped and looked at her.

“Okay, this is far enough,” he said. “What is going on here? Who called you out here?”

She locked eyes with him again.

“Listen, what I tell you here has to remain confidential,” she said. “For now.”

“Look, Rachel, I don’t have time for-”

“ Stanley Kent is on a list. When you or one of your colleagues ran his name on the National Crime Index Computer tonight a flag went up in Washington, DC, and a call went out to me at Tactical.”

“What, was he a terrorist?”

“No, he was a medical physicist. And, as far as I know, a law-abiding citizen.”

“Then what’s with the radiation rings and the FBI showing up in the middle of the night? What list was Stanley Kent on?”

Walling ignored the question.

“Let me ask you something, Harry. Has anyone checked on this man’s home or wife yet?”

“Not yet. We were working the crime scene first. I plan to-”

“Then I think we need to do that right now,” she said in an urgent tone. “You can ask your questions along the way. Get the guy’s keys in case we need to go in. And I’ll go get my car.”

Walling started to move away but Bosch caught her by the arm.

“I’m driving,” he said.

He pointed toward his Mustang and left her there. He headed to the patrol car, where the evidence bags were still spread on the trunk. As he made his way he regretted having already cut Edgar loose from the scene. He signaled the watch sergeant over.

“Listen, I have to leave the scene to check on the victim’s house. I shouldn’t be gone long and Detective Ferras should be here any minute. Just maintain the scene until one of us gets here.”

“You got it.”

Bosch pulled out his cell phone and called his partner.

“Where are you?”

“I just cleared Parker Center. I’m twenty minutes away.”

Bosch explained that he was leaving the scene and that Ferras needed to hurry. He disconnected, grabbed the evidence bag containing the key ring off the cruiser’s trunk and shoved it into his coat pocket.

As he got to his car he saw Walling already in the passenger seat. She was finishing a call and closing her cell phone.

“Who was that?” Bosch asked after getting in. “The president?”

“My partner,” she replied. “I told him to meet me at the house. Where’s your partner?”

“He’s coming.”

Bosch started the car. As soon as they pulled out he began asking questions.

“If Stanley Kent wasn’t a terrorist, then what list was he on?”

“As a medical physicist he had direct access to radioactive materials. That put him on a list.”

Bosch thought of all the hospital name tags he had found in the dead man’s Porsche.

“Access where? In the hospitals?”

“Exactly. That’s where it’s kept. These are materials primarily used in the treatment of cancer.”

Bosch nodded. He was getting the picture but still didn’t have enough information.

“Okay, so what am I missing here, Rachel? Lay it out for me.”

“ Stanley Kent had direct access to materials that some people in the world would like to get their hands on. Materials that could be very, very valuable to these other people. But not in the treatment of cancer.”