Touch of Red (Tracers #12)(8)

“When I first entered the home, I noticed a key on the counter.”

“You guys collected it for evidence before we could test it out,” Sean said.

“I tested it,” Brooke told him. “It fits the back door. When I entered the house, I also noticed the pantry door was open and there were some crumbs on the floor.”

“Wait,” Sean said. “You’re saying—”

“I think the child was standing in the pantry, hiding there behind the door while the murder took place a few feet away.”

Silence fell over the room.

“Why do you think it’s a kid?” Ric asked. “If someone was there, it could have been an adult.”

“It wasn’t.”

More skeptical looks.

“The prints on the pantry door were low, about twenty-eight inches off the ground. So, that’s either a child or a short adult. As I was dusting the door, I noticed cookie crumbs on the floor—frosted animal cookies—and I immediately thought about a kid standing there. So on a hunch I took the door, the cookie package, and the spare key back to the lab and confirmed it: nine good prints, all belonging to a child. Two on both the key and the cookie package and five prints on the door.”

“Wait a minute.” The lieutenant held up his hand. “Even if you’ve got some kid’s prints in the kitchen, what makes you assume the kid’s a witness?”

“I don’t assume. I know.”

“How can you be sure this child was there last night?” Ric asked. “Maybe it’s the victim’s niece or nephew, or some kid she babysits, and the prints were left a week ago.”

“They weren’t,” Brooke said firmly.

Sean darted a look at Ric, and Brooke felt a surge of frustration.

“Just . . . listen.” She scooted forward in her chair. “Do you all understand how fingerprints work?” She glanced around the table, but no one would admit to not knowing. Of course not. “Fingerprints are basically ridges on the skin. Latent prints, the ones invisible to the naked eye, are made up of oil and sweat and other substances that we deposit on a surface when we touch something. Children’s prints—like the ones at that murder scene—are different from adults’ prints. The fatty acids are more volatile and break down faster. So kids’ prints are much more fragile than adults’ are, which is why in kidnapping cases you can fingerprint a suspect’s vehicle days or even hours after a child was in it and not get anything. It depends on time elapsed, heat, humidity—a lot of things—but the prints can just vanish.”

Brooke paused to let all that sink in.

“That explains the rush.”

She turned to Sean. “What?”

“You left the crime scene before everyone else.”

She nodded. “I had to get back to the lab quickly to run everything using a different method. We’re talking about very delicate evidence. Powders and brushes can be destructive. So I used a technique called infrared microspectroscopy. You visualize the print by using beams of infrared light to detect substances, such as salts, fatty acids, and proteins.” She pulled a photograph from her file. The bright-colored image was of a thumbprint from the pantry door. “See the ridge detail? The red and orange indicate oil from the skin.”

She slid the photo to the lieutenant, who passed it to Ric.

“My tests confirmed that we are, in fact, dealing with the prints of a prepubescent child. I performed the procedure again this morning, and the red and orange have already faded significantly as the biological material breaks down, making the minutiae of the print much harder to discern.” She passed them another photo. “See? If those fingerprints had been left weeks or even days ago, they’d be long gone.”

Sean watched her, but his expression was guarded.

“Walk me through it,” Callie said. “Let’s say it’s a boy. You think he let himself in with a spare key and then . . . what?”

“The spare key would be my guess, yes. He lets himself in the back door, which has a glass window. Then let’s say he goes to the fridge and grabs a root beer. And then he goes to the pantry and reaches for some cookies. He’s in there munching on one when Samantha Bonner pulls into the driveway. Moments later, she’s attacked on her doorstep, and the kid is cowering behind the pantry door, watching or at least hearing the whole thing. After the killer flees, the kid steps outside—explaining the open back door—and finds Samantha dead.”

No one said anything. Brooke wondered if they were thinking about what had had her tossing and turning most of the night. The child would have been utterly terrified.

“A potential eyewitness is big,” Ric said. “We need to interview the victim’s friends and family and find out what kid could have been at her house last night. And maybe the kid was there with a parent.”

“It would have to be a parent there on foot,” Callie said. “I mean, if the killer sees some car parked in front of her house, he’s not going to carry out the attack, right?”

Brooke let out a breath. Buy-in. Finally. They were at least pretending to accept her findings.

She glanced at her watch and pushed her chair back.

Sean gave her a sharp look. “Where are you going?”

“I need to get back to the lab.”