The Square Root of Murder (Professor Sophie Knowles)

them.”
    “You mean tell them about the boxes and all. Didn’t you tell him today?”
    “I don’t even know what the ‘all’ is, by the way,” Bruce said. I wasn’t shocked that Bruce was aware that I’d been holding back from him. He’d had a lot of experience with my moods, tone of voice, and signs of tension. “And no, I didn’t tell him about the boxes. That’s for you to do.”
    “I don’t see the boxes as all that important anyway,” I said. “The crime scene people had already been through Keith’s office and taken whatever they wanted. Eventually Woody or some other faculty member would have cleaned out the rest of the stuff. Why not me?”
    “I’ll buy that,” he said.
    “I hope the dean does tomorrow.”
    “It’s not as if you’re withholding evidence.”
    “I might be.”
    Bruce put his fork down. His heavy eyebrows moved closer together.
    “Hit me with it.”
    What kind of psychology training were medevac personnel given that Bruce was able to turn things around and I ended up spilling everything first?
    I told Bruce about the parade of people who walked through the crime scene and even messed with it, as Woody did.
    “Soph,” was all he said.
    “I know, I know. I’ll go by tomorrow right after I see the dean, I promise. Now it’s definitely your turn.”
    “Well, I’m glad to report that the cops are on target. They’re putting the murder at sometime after one o’clock, which fits with Rachel’s finding him already dead at quarter to two.”
    Whew. The police figured it out on their own. I felt marginally better. All I needed to do was give them the curious timelines for the cake and the yellow sheets.
    “Are the results in on the poison? Can they tell what it was that killed him?”
    “Potassium chloride.”
    “Like the label on the bottle on Keith’s desk.”
    “Uh-huh. I actually saw the crime scene photo of the bottle. It was transparent, with a white label, and it was in solid form, a granular white powder. But it’s very soluble in water. I guess it’s common in a chem lab. We probably even have some in the supply trailer.”
    I thought of Rachel’s missing key to the cabinet in the main chemistry lab. “So someone used Rachel’s key to get it out of the cabinet, melted it in water, and put it in a syringe?”
    “I don’t think melted is the right word.”
    I shrugged it off. “Close enough. Where did all that happen? I mean, do you just go to the sink and mix it all in a glass?”
    “I haven’t a clue. Virge says there was no such evidence in the Franklin Hall chem lab. No glass, so to speak, as in your scenario, or stirrer. They think the actual mixing was done off-site.”
    “Then why would the killer put the bottle on the desk? Isn’t it obvious it was just a plant, to point to Rachel?”
    “I don’t think Virge has a theory on that. Wherever it was prepared, apparently Keith was given an injection of an unnaturally high concentration, about the same as they use for the death penalty.”
    “He’d have to be unconscious, don’t you think? Otherwise he’d fight off the attacker.”
    “Or else it was a surprise. Someone he knew got close and . . .” I shuddered. Bruce put his fingers on the side of his neck. “The injection site was right here. The heart just stops.”
    “The heart, or Keith’s heart?”
    Bruce took my hand across the table. “Sorry, Sophie. They’re saying it was very quick, anyway, that he didn’t suffer for a long time. Some comfort, huh? I know it’s tough on you, even though you weren’t best friends.”
    “Some people think we were.” I told Bruce about the many nice words for Keith that came from his cousin and Woody, how generous he was behind our backs.
    “Who would have guessed?”
    “Not me,” I said.
    I hadn’t given much thought to the biological details of Keith’s death. While I’d certainly heard of potassium chloride in connection with fertilizer, it wasn’t in my skill set to remember much of chemistry and chemical formulas. Way too complicated. Besides, chemistry was dangerous. One little atom off and a substance went from harmless to lethal. There was sodium chloride, which was simply salt, and potassium, which I believed was in bananas, but potassium chloride was something that could kill.
    I found it amazing that an ingredient commonly kept in a college chemistry laboratory, where students and teachers walked around every day, could be lethal. I knew it in theory, I supposed, a