“Doug, move that a little to the left,” Charlie said. He’d divided the crime scene into three areas: the hall, Jason’s room, and the bathroom. They had all agreed that their best bet was finding something in the hallway. The group of assembled men hadn’t needed to articulate the problems associated with looking for DNA in a communal boys’ bathroom, but Will could tell none of them were looking forward to crawling around on that particular floor.

Charlie tinkered with the light on the tripod. “This is the ME-RED I told you about.”

“Nice.” Will had already gotten an earful about the extremely fascinating qualities of the Mobile Electromagnetic Radiation Emitting Diode, which as far as Will could tell was fancy jargon for a gigantic black light that had a longer range than the Wood’s lamps that had to be carried around by hand. The lights would pick up visible traces of blood, urine, and semen, or anything else that contained fluorescent molecules.

For the traces that were less visible, Charlie and his team had sprayed the hallway with Luminol, a chemical that reacts to the presence of iron in blood. Crime shows had made the general public well aware of the blue glow emitted by Luminol when the lights were turned off. What they hadn’t shared was that the glow usually lasted around thirty seconds. Long-exposure cameras had to be used to record the process. Charlie had set these up on tripods in all four corners of the hallway and staggered more around the entrance to Jason’s dorm room. For good measure, he had tilted the security camera back down to capture it all in real time.

Will stood at the mouth of the stairs, watching the team make last-minute adjustments. He wondered if the murderer had paused here on the stairs to psych himself up for the kill. It was all so premeditated, so well thought out. Enter through the back door. Push up the cameras. Go up the stairs. Weapons in hand. Gloves on. Plan ready: Incapacitate Jason with the bat. Drag him to the bed. Cover him with the blanket. Stab him repeatedly. Hide the blanket in case it contained any trace evidence. Go back down the stairs. Leave by the back door.

Was it really as calculated as that? What went through a person’s mind before they went to someone’s dorm room, their home, and fractured their skull with a baseball bat? Would the killer’s pulse quicken? Would his stomach tighten the way Will’s did when he thought about the gruesome crime scene? There had been so much blood, so much brain and tissue, spattered around the room that Charlie and his team had been forced to make a grid so that they could clear a path to fully document the carnage.

What kind of person could stand over that bed and methodically stab another human being?

And what about poor Jason Howell? Lena was probably right that the killer had known Jason well enough to hate him. Despise him. What kind of trouble had the kid gotten himself into that he would become the object of such fury?

“I think we’ve got it.” Charlie grabbed a handheld video camera and pulled Will toward Jason’s room. He told Doug, “Go get the lights.” Doug took off down the stairs and Charlie explained the plan to Will. “First we’ll see what the Luminol brings out, then we’ll go to the black light.”

“Ready?” Doug called.

“Ready,” Charlie yelled back.

The hall went dark. The Luminol responded quickly. Dozens of small, elongated circles glowed blue just outside Jason’s open doorway. They were smeared where the killer had tried to wipe them up, but the pattern was easy to follow. The drops revealed his movements. After stabbing Jason to death, the killer had walked out of the room, heading toward the stairs, then changed his mind and doubled back toward the bathroom.

“The original plan was probably to take the blanket with him,” Charlie said. He held the video camera low, documenting the drips. Will could hear the steady, slow click of the long-exposure cameras capturing the evidence.

He asked, “What about this?” A larger stain, more like a puddle, was on the floor just beside the bathroom entrance. Three feet above it was a patterned mark on the wall.

Charlie twisted up the LCD screen of the camera. Will saw the images in double as he recorded the luminescent blobs. “Our killer comes out of the room, heads toward the stairs, then he realizes the blanket is dripping. He goes toward the bathroom, but first—” Charlie pointed the camera toward the glowing stain on the floor. “He leans something against here. I’d guess a bat or a club. That’s the mark on the wall.” Charlie zoomed in close to the wall where the top of the weapon had rested. “Uh-oh, fingerprint.”

Charlie got down on his knees and pointed his camera at an almost perfect circle. “Gloved, it looks like.” He zoomed in closer. The glowing dot started to fade. “We’re losing it.”

The Luminol’s reaction time varied depending on the content of iron in the blood. The dot slowly disappeared, then the puddle on the floor was gone. Charlie muttered a curse as the hall was plunged back into darkness.

Charlie rewound the camera to look at the print again. “He was definitely wearing gloves.”

“Latex?”

“Leather, I think. There’s a grain.” He showed Will the LCD, but the light was too intense for him to see anything but a blob. “Let’s see if it still shows up under the diodes.” He called, “Black light, please.”

There were a couple of popping noises, then a steady hum. The hallway lit up like a Christmas tree, illuminating every protein-based fluid ever left here.

“Impressive, right?” Charlie’s lips glowed a bright blue, probably from the Vaseline in his lip balm. He knelt down on the floor. The blood trail that had glowed so brightly minutes before was barely visible. “Our killer did a good job cleaning up after himself.” He took a few more photographs. “Good thing he didn’t use bleach or we wouldn’t be able to see any of this.”

“I don’t think he planned to leave a mess,” Will said. “Our guy is careful, but the only things he probably brought with him were the weapons—the knife and a bat or club. He used the blanket on the bed to catch the spatter. He tried to leave with it, then like you said, he changed his mind because it was dripping.” Will felt himself smile as he remembered, “There’s a supply closet beside the stall where I found the blanket.”

“You’re a genius, my friend.” They both went into the bathroom. Charlie flipped on the lights. Will clamped his hands over his face, feeling like his eyeballs were being stabbed.

“Sorry about that,” Charlie apologized. “I should’ve warned you to close your eyes and open them slowly.”

“Thanks.” Spots exploded in front of his eyes with every blink. Will put his hand on the wall so he wouldn’t trip over his own feet.

Charlie stood in front of the supply closet with his video camera. “We can check the photographs, but I’m sure this door was closed when we got here.” His hands were still gloved. He carefully turned the knob.

The closet was shallow, a metal shelving unit taking up most of the space. There was nothing unusual about the contents of the shelves: gallon jugs of cleaning products, a box of rags, sponges, two toilet plungers, a mop tucked into a rolling yellow bucket. Two spray bottles hung from a bungee cord on the back of the door. Yellow liquid for spot-cleaning stains. Blue liquid for windows and glass.