Whether it actually did or not, she had no way of knowing, but it was as good a guess as any.
***
Zoe had been worried for a brief moment that she might be waking Dr. Applewhite up, but being held by the FBI for the first time in your life was not a soothing experience. She had been sitting awake, staring at the walls, with nothing else to do to pass the time.
“I am sorry for all of this,” Zoe said quietly, sitting opposite her mentor with a steaming cup of coffee in front of both of them. The staff on duty had insisted that if she wanted to talk to someone being held overnight, it had to be in a proper interrogation room. It had to be recorded.
It wasn’t the way she would have preferred to do things, but it would have to do.
“The wheels of justice have to keep on turning.” Dr. Applewhite smiled, tucking her hair behind her ear. She didn’t sound particularly happy, even if her lips were curved up into the right shape.
“Is that a quotation?”
“At this stage, I don’t even know.” Dr. Applewhite sipped at her coffee. “I’m tired, Zoe. It’s been a long day.”
The guilt hit her even harder. What more could she do? It wasn’t as if Zoe had been sitting around at home, or had resolved just to leave Dr. Applewhite in a cell all night. She had been out there, trying to find a solution for this thing. It just hadn’t happened.
“I am sorry,” Zoe murmured again, wondering if at this point it even made any difference. She continued louder, wanting to take action now more than ever. “I have been working on a theory. I thought you might be able to help me figure out who the culprit could be.”
“Anything to get me out of here quicker.” Dr. Applewhite sighed. “Let’s hear it, then.”
Zoe nodded. “I think the killer has recently suffered some kind of neurological change. One side effect of this would be something like aphasia, dyslexia, dyscalculia. Something that prevents him from being able to write things out properly. That is why the equations do not make sense, and also why the violence has started happening now. I am willing to bet that before this traumatic event, whatever it was, the killer has no history of violent behavior.”
“But?”
“But we went to the hospital where Dr. North worked, and there was nothing in the records. We cannot find anyone who fits the criteria of this kind of recent development alongside the appropriate height, weight, and age.”
“Hmm.” Dr. Applewhite took another sip of her coffee. “Well, the theory works. It doesn’t sound like it should be wrong.”
“That is why I thought you might be of some help. I need you to think back, wrack your brains. Is there anyone, either in the academic world or in mathematical circles? Anyone who was rumored to be a bit strange, or stories that sound a bit off? Glaring mistakes, problems with speech, anything like that?”
Dr. Applewhite sat back in her chair, her eyes roving across pictures that Zoe could not see as she thought. “Mistakes, yes. But those are just part of mathematics. That’s what happens when you try to work on something difficult, something theoretical. My own formula was flawed, after all.”
“Not something like that—not a missed calculation or a failure to carry the one. More like things being written down in the wrong way. Numbers reversed, or put out of order, for example. The way that the equations on the bodies were unbalanced.”
“I work too much to stay up to date with all of the national journals, to read something as embarrassing as that,” Dr. Applewhite protested. “I suppose it would have made a scandal, but I haven’t heard about anyone messing up that badly.”
“It does not need to have been published. It could have been coursework—something a professor at the college noticed and mentioned to you. Someone brilliant that suddenly made mistakes. It has to be a big fall from grace for him to be this angry. If I suddenly lost the ability to draw, given my already limited art skills, I do not think that I would be upset.”
“That’s very insightful. You’ve been working on your empathetic understanding of others, haven’t you?”
Zoe couldn’t say that she had, but maybe just being around someone like Shelley was enough to help her understand more about human nature, in herself and others. “That is not the point. Think back. Stories, rumors. Hints. Anything you heard in passing. It does not even have to be concrete.”
“Look, I just can’t think of anyone,” Dr. Applewhite said. “Maybe it would be better to ask the professors. Or another neurologist.”
“The change might not have been completely obvious,” Zoe pressed. She couldn’t give up. Not when they were this close to getting somewhere. If she wasn’t right about this, then Dr. Applewhite could go all the way to trial. “The brain—it does not always work in the ways that we expect. Maybe he could have hidden his communication problems by talking less, going underground or something. But someone would have noticed. His personality would be different, he would be quieter. Not as able to perform at the level he was at previously. A star student, suddenly not on the scene anymore.”
“The only students that normally get referred to me by others are the ones who show signs of synesthesia. Not very many, as you might appreciate. Even when we talk about these things, it’s not normally by name.”
“I don’t even need a name,” Zoe pleaded. How could Dr. Applewhite not see that she needed her to try harder, to dig deeper? This could mean the difference between going home in the morning and staying here to await trial, if the killer didn’t strike again. “Just a hint. Someone else we can talk to who might know something. Anything at all.”
Dr. Applewhite was frowning, looking off into the distance. “What was that you said about going quieter?”
“A—a star student,” Zoe said, desperately trying to remember her exact words. “His personality would change and he would go quiet. No longer performing at the same level.”
Dr. Applewhite paused, rubbing her lips with the side of her index finger as she thought. “I… I think there might have been something like that,” she said.
“Who? When?” Zoe practically felt like she was about to leap across the table and rip the words out of Dr. Applewhite’s head herself, if that would make them come out quicker.
“I don’t know why I didn’t think of it before. It was—yes—I’m sure of it—it was Ralph Henderson.”
“The English professor who died?”
“There was a student of his, someone who showed a lot of promise. Ralph told me about how it was such a shame. He had been in an accident or something—a car crash or something like that. Ralph was thinking of recommending him for some advanced training, getting him to work on more theoretical stuff, but after the accident he retreated. He didn’t say anything about the effects on his work—given that he was teaching English, not math—or about him being unable to communicate. Just that he wasn’t so active on campus, retreated into himself, started missing lectures.”
“Do you know his name?” This was it. The million-dollar question. If they could just find him…
Dr. Applewhite screwed up her face. “Oh, god, this was a while ago… and I wasn’t even really listening at the time. Let me try to think. I didn’t get any of the details—god, what did he keep calling him?”