The Apprentice: A Rizzoli & Isles Novel

one. It doesn’t match either the victim’s head hair or the hairs we got from the wife’s hairbrush.”
    Rizzoli moved the field, scanning the hair shaft. “It’s definitely human?”
    “Yes, it’s human.”
    “So why can’t it be our perp’s?”
    “Look at it. Tell me what you see.”
    Rizzoli paused, calling back to mind all that she had learned about forensic hair examination. She knew Erin must have a reason for taking her so systematically through the process; she could hear quiet excitement in her voice. “This strand is curved, degree of curl about point one or point two. And you said the shaft length was twenty-one centimeters.”
    “In the range of a woman’s hairstyle,” said Erin. “But rather long for a man.”
    “Is it the length that concerns you?”
    “No. Length doesn’t tell us gender.”
    “Then what am I supposed to focus on, anyway?”
    “The proximal end. The root. Do you notice anything strange?”
    “The root end looks a little ragged. Kind of like a brush.”
    “That’s exactly the word I would use. We call that a brushlike root end. It’s a collection of cortical fibrils. By examining the root, we can tell what stage of hair growth this strand was in. Care to venture a guess?”
    Rizzoli focused on the bulbous root end, with its gossamerlike sheath. “There’s something transparent clinging to the root.”
    “An epithelial cell,” said Erin.
    “That means it was in active growth.”
    “Yes. The root itself is slightly enlarged, so this hair was in late anagen. It was just ending its active growth phase. And that epithelial cell might give us DNA.”
    Rizzoli raised her head and looked at Erin. “I don’t see what this has to do with zombies.”
    Erin gave a soft laugh. “I didn’t mean that literally.”
    “What did you mean?”
    “Look at the hair shaft again. Follow it as it leads away from the root.”
    Once again, Rizzoli gazed into the microscope and focused on a darker segment of the hair shaft. “The color’s not uniform,” she said.
    “Go on.”
    “There’s a black band on the shaft, a short way from the root. What is that?”
    “It’s called distal root banding,” said Erin. “That’s where the sebaceous gland duct enters the follicle. Sebaceous gland secretions include enzymes that actually break down cells, in a sort of digestive process. It causes this swelling and dark band formation near the root end of the hair. That’s what I wanted you to see. The distal banding. It rules out any possibility this hair is your unsub’s. It may have been shed from his clothes. But not his head.”
    “Why not?”
    “Distal banding and brushlike root ends are both postmortem changes.”
    Rizzoli’s head snapped up. She stared at Erin. “Postmortem?”
    “That’s right. It came from a decomposing scalp. The changes in that strand are classic, and they’re pretty specific for the decomposition process. Unless your killer has risen from the grave, this hair could not have come from his head.”
    It took a moment for Rizzoli to find her voice again. “How long would the person have to be dead? For the hair to show these changes?”
    “Unfortunately, banding changes aren’t helpful in determining the postmortem interval. It could have been pulled from the deceased’s scalp anywhere from eight hours to several weeks after death. Hair from corpses embalmed years ago could also look like this.”
    “What if you pull someone’s hair out while they’re still alive? Leave those hairs lying around for a while? Would the changes show up then?”
    “No. These decompositional changes only appear while the hair remains in the dead victim’s scalp. They have to be plucked out later, after death.” Erin met Rizzoli’s stunned gaze. “Your unknown subject has had contact with a corpse. He picked up that hair on his clothes, then shed it onto the tape, while he was binding Dr. Yeager’s ankles.”
    Rizzoli said, softly: “He has another victim.”
    “That’s one possibility. I’d like to propose another.” Erin crossed to another countertop and returned with a small tray bearing a section of duct tape lying adhesive-side up. “This piece was peeled off Dr. Yeager’s wrists. I want to show it to you under UV. Hit that wall switch, will you?”
    Rizzoli flipped the switch. In the sudden darkness, Erin’s small UV lamp glowed an eerie blue-green. It was a far less powerful light source than the Crimescope that Mick had used in the Yeager