“I don’t look at it like that. I’m just another sergeant given the honor.”

“Bullshit,” Mooney said. “This is big. You’re a groundbreaker. It’s important to the other officers coming up in the department.”

“There are some people out there saying I only got the job because I’m black.”

“Give me the names of the bozos talking smack, and I’ll crack them over the head. You got the position because you’re the best man. This ballistics unit has been messed up for years. How many guns have been secured here as evidence and turned up missing?”

“My first priority is to inventory, box up, and bar code everything for the evidence management system.”

“You’re the best. And you’re going to prove it by helping me out with a case.” He handed one of the coffees to Stone.

Stone led Mooney back to his office. “What case?”

“Josh Kipping. Alves brought you four slugs and some autopsy photos yesterday.”

“The Prom Night Killer.” Stone sat behind his desk and removed the lid from his coffee. “Interesting case. Multiple shots. One entry. Angel told you I matched the projectiles to the evidence from ten years ago?”

“That’s helpful.” Mooney flipped the cover off his coffee and took a sip. “But I already knew it was the same guy. What’s your theory on the single entry wound and the number of shots fired?”

Stone took a sip. “I think he’s using a machine gun.”

“A machine gun?” Mooney almost coughed up his coffee.

“Not a regular machine gun. Not something that was manufactured as such.” Stone put his cup down and got up from his chair. “Come with me. I want to show you something.”

Mooney followed him down the hall to the Secure Firearm Evidence Room where the guns were stored. Stone walked down the rows of shelves and came out with an evidence box. He led Mooney to the test firing room.

“What do you have there?” Mooney asked.

Stone placed the box on a table and removed the gun. “It’s an interesting case from a few years back, before I made sergeant, when I was just a detective examining firearms and testifying in court. It’s a twenty-two caliber Berretta semiautomatic, altered to fire fully auto.”

“I’d like to see how to do that.”

“Let me show you.” Stone took a stack of photos from the box and spread them on the table. “I had a second gun that was in pristine condition. Took the two of them apart and took some comparison photos. You can see in the pictures that the trigger bar arm has been cut by about a third in the altered firearm. You know how this type of weapon is supposed to work.”

Mooney nodded, focusing on the photos.

“When the gun is fired, the slide is forced back, loading the next round from the magazine and resetting the hammer. The bar arm’s supposed to hold the hammer in the cocked position until you pull the trigger again to fire the next round. With the bar arm cut short, the hammer doesn’t stay in the cocked position. The weapon keeps firing as long as you hold the trigger. It keeps firing until the clip is empty. Nine rounds. Unless it jams.”

“Does it jam?”

“Every time. I’ve never gotten it to fire the full nine rounds, but it always manages to pump out three, four, even five rounds.”

“Like we’ve found in each of the victims.”

“Correct. Let me show you.” Stone opened a file cabinet drawer, shuffled through some boxes and took out some.22 caliber ammunition. He fed nine rounds into the clip and slid it into the handle of the gun. He put on his sound-deadening headphones and handed a pair to Mooney before making his way to the projectile recovery tank. He put on his safety glasses. “Watch carefully, Wayne. It’s going to come out in one burst. To an untrained ear it would almost seem like one shot, but you’ll see and hear that it isn’t. The first time I fired this thing, I almost had a heart attack. I didn’t know it had been altered. I was just testing it to see if it was a working firearm and it took off on me.”

Stone positioned himself, the gun in his right hand, supported by the left. Then he squeezed the trigger. Mooney saw the flash from the barrel of the gun. He could hear it was multiple shots, but he wasn’t sure how many. He tried to count the shell casings as they were ejecting, but it happened too fast, the casings scattering on the floor.

Stone removed his ear protection. “I think that was five. That’s what it felt like.” He bent over and picked the casings up off the floor. “Confirmed. Five.”

“The bullets that killed these kids are also twenty-two cal. Were they fired from a Berretta?”

“I think so. Six lands and grooves with a right twist. Consistent with a Berretta. But I’d want to see the weapon to make a positive match. If this killer has a gun like this, altered in the same way, it would explain why you have multiple shots, but never the same number, and only one entry wound. And tattooing consistent with this gun barrel.” Stone placed the gun down on the table. “Wayne, you know this gun serves only one purpose. It’s a hit man’s weapon. Small caliber, so it doesn’t make too much noise. When you pull the trigger, it sounds like one round being fired instead of four or five. It fires so fast that the last round would be fired before the first casing hits the ground. And you know from experience that small caliber rounds can cause more internal damage to the victim.”

Stone picked the gun up again. “And this gun would be useless in a gunfight. You basically get one pull of the trigger and you discharge all nine rounds at once or the gun jams up. Either way, if you miss your target, you’re out of luck. The fight’s over and you’re a dead man.”

Alves rang the buzzer outside the crime lab. He was tired. Putting his head down on a conference room table for a couple of hours didn’t qualify as a good night’s sleep. Having nightmares and picturing your sleeping family alone in a dark house didn’t help.

“Can I help you?” Alves heard the pleasant voice behind him. A young woman opened the door to the crime lab. He had never seen her before. Blond hair, pulled back in a ponytail. She looked like a teenager, but she was probably a new criminalist, straight out of college with her biology degree. The new hires seemed to be getting younger.

“I’m looking for Eunice Curran?” Alves said.

“And you are?”

“Detective Alves. Homicide.” He had his gold badge clipped to his belt.

She left him at the reception desk and went back to check with Eunice. Following protocol. Good for her. Once she’d cleared everything with the boss, she let Alves enter the inner sanctum of the DNA lab and the evidence examination rooms. Eunice Curran was in one of those rooms, laying out the evidence she had recovered over the last couple of days.

“Hi there, handsome,” she said. “I’ve been expecting you. Like clockwork, you always show up the morning after…an autopsy, that is. But you’re usually not this early.”

“Never made it home last night.”

“I saw your buddy Sergeant Mooney across the hall,” she said. “That’s two days in a row I’ve seen you guys together. People are starting to talk.”

“Nothing to talk about. Mooney’s back in Homicide.”

“Good to hear. Let me show you what I’ve got…the evidence, that is.” She brought over two paper evidence bags. He could see the change in her face, in the tone of her voice. She was discussing her work now, so no more fooling around. “Here’s the wire that was used to secure the victims. I’ve kept them separate. It’s all identical black telephone wire, one of the fine, multicolored wires you find inside a telephone line. I pulled the evidence from the old cases. It’s a match. It looks like he’s taking ordinary telephone line, slicing off the outer casing and using the black wire inside. He probably likes it because it’s less visible to the naked eye than the colored wire, the reds, greens and yellows. It definitely serves its purpose. Thin, but sturdy.”