The Square Root of Murder (Professor Sophie Knowles)

he was dead. I picked up the food and ran out. Then I put the plate and soda outside the door, to make it look as if I’d never gone in.”
    I let out a big sigh, feeling like I’d been at the scene myself and just got out in time before losing my lunch. I threw up my hands. “Why didn’t you call the police, Rachel? Or at least let someone know? Anyone.” I tried to keep my voice even.
    “Everyone knows how bad things are going with my research, and you said yourself how I’ve been mouthing off lately. I was scared someone would think I did it.”
    I didn’t feel it necessary to remind her that a very important someone did think she did it. And maybe wouldn’t have, if she’d simply reported what she walked in on. She might have been just another suspect, instead of sticking out like a prime number.
    “You have to tell the police. You have valuable information that they can use in a murder investigation. Don’t you see how important this is?”
    “It’s not like I actually saw anything.”
    “You saw a dead body at a certain time and place yesterday. If nothing else, that helps establish a timeline.”
    “I guess.”
    “You guess?” I paused. The last thing Rachel needed was my anxiety-ridden response. I lowered my voice. “You have to promise me that you’ll go to the police station. In fact, you can come with me this afternoon. I have an interview there myself.”
    I’d made it sound as though I’d initiated the meeting with Archie. Archie cop, me reporter.
    Rachel pointed across the room to an old, round fan on a high stand. “It’s roasting in here. Can we turn that on?”
    “If it works.” No promises from her about making a trip downtown, I noticed.
    We shared the chore: moving the fan, finding a socket, adjusting the speed—all very legitimate distractions while Rachel stalled and stalled. I tried to think of another occasion when she’d put off a distasteful task. I couldn’t. Not even when she worked on the biology floor.
    “What else can you remember? What did the office look like?”
    “Just his regular office stuff. But his desk was a mess and, you know, it’s usually in perfect order.”
    “Did the police tell you what they found?”
    “They didn’t tell me much, except that Dr. Appleton had been poisoned, and that they were talking to everyone in the building. But I knew it was more than just routine with me because they asked me things like did I work more closely with Dr. Appleton than the undergraduates, and did I have a key to the chemical cabinet.”
    “What did you tell them?”
    “I just said how Dr. Appleton was a strict teacher, but people respected him for it, and I was glad I had him for an adviser. I guess all that was another lie, but I wasn’t going to make myself look worse.”
    “And the key to cabinet?
    “I told them the truth but then when they asked me where it was, I couldn’t find it. It’s always on a separate key ring in my purse, the one you gave me, with the metal pi symbol on it? But I went to get it, and it wasn’t there, Dr. Knowles. I lost it.”
    Or someone took it.
    I didn’t know too many legal terms, but premeditated was one that stood out. If someone went to the trouble of stealing Rachel’s key ahead of time, then Keith’s murder wasn’t a random act, in the heat of an argument, but a well thought out frame-up of Rachel.
    From outside, I heard the sound of a plane taking off. At least this time it was not an emergency mission, but one of the many small plane owners treating friends or relatives to a bird’s-eye view of the beautiful New England landscape.
    “Rachel, you said Dr. Appleton’s desk was a mess. Did you see anything in particular that was . . . out of place? Papers strewn about? Anything like that?”
    She frowned, thinking, then shook her head. “Not that I remember. I think his lamp was knocked over, but I’m not sure. I was only in there, like, a minute.”
    “So no yellow computer paper everywhere, for example?”
    “You mean like what we use for drafts?”
    “Maybe.”
    Rachel bit her lip. More thinking. “No, I think I’d remember that.”
    I tried to keep track of the inconsistencies without taking notes, which I was afraid would intimidate my witness. The crime scene people had not found the cake Rachel said she left outside the door, but they had found pages of Rachel’s thesis on yellow paper, which Rachel had not seen.
    A medium hard puzzle, I told myself, not impossible, once I have a