In Death 24 - Innocent in Death

the center.”
    She stopped walking atvertex to stare at him.
    “Then, as every central angle cuts the circle in two arcs, there’d be the minor arc-the smaller, which would be less than one hundred and eighty degrees, and the major, the larger, which is always more.”
    “Jesus.”
    He grinned, shrugged. “I always liked geometry.”
    “Geek.” She scowled down the hallway. “Now I forgot what I was doing.”
    “Or you may be after the tangent,” he said, unconcerned. “The point of tangency would be the point where a line intersects the circle at precisely one point, and one only.”
    “Shut up.”
    “You asked. Of course, your shape might be a triangle, say, and in that case-”
    “I’m going to draw down on you in five flat seconds and stun you senseless.”
    “You know what I liked even more than geometry? Finding the blind spots on the security cams,” he said. “Which, in fact, geometry helped me with. Then snagging some sweet young thing, and-”
    He snagged her, whipped her around, back to the wall, and, grinning, kissed her lavishly.
    His mouth managed just what geometry did. It fuzzed her mind.
    “Work now, tonsil hockey later.”
    “You romantic fool. Now then, I think I understand what you’re trying to figure out, and it’s more to do with intersections and betweenness.”
    She actually had to press her fingers under her eye to still a twitch. “‘Betweenness’ can’t possibly be an actual word.”
     
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    “It is, in fact, in math language. And I think it would be your first victim’s classroom.
    That’s the point between the others. And also, I’d think, where your lines intersect, in the first theorem.”
    “Let’s just leave the higher math out of it because it’s going to separate my mind from my body, and I’d rather save that for sex. Foster’s classroom.” She gestured. “Which was empty for at least fifty minutes, twice that day-before class and during his fourth period, giving the killer ample opportunity to doctor the go-cup, or simply replace it. I’m going to push on the replacement angle tonight. Maybe get lucky there. It was inscribed with his name. Anyway…”
    She walked over, uncoded the seal, opened the door. “Other classes are in session, including the second vic’s. Here.” She walked over, opened the door on Williams’s classroom. During the second fifty-minute segment when Foster’s classroom was unoccupied, Williams leaves his classroom for about ten minutes. Used the bathroom, he claimed.”
    “Which gives you a segment line, from point to point. Opportunity and motive.”
    “Yeah. Means is yet to be proven. I can’t tie the poison to Williams. How’d he get it, why would he choose it? Meanwhile, there’s some foot traffic. There’s a janitor in the students’ bathroom-male. He’s clean and clear. No record, no motive, excellent work record, married, father of three, and two grandkids who attend this school.”
    “But he’s another intersection.”
    “Yeah, yeah. He sees, and is seen by Mosebly, Hallywell, Williams, and Dawson. Then by Rayleen Straffo and Melodie Branch. Each pass by at some point, with Dawson, um, intersecting again with the two students. On the lower level, Hallywell intersects with two other students.”
    “There’s also your unknown.” Following her equation, Roarke added to the data. “The possibility someone not identified ran a parallel line. A segment that didn’t intersect with another segment, but arrived at your center.”
    “The outsider. Allika or Oliver Straffo, for instance, both of whom could-with forethought and planning-have bypassed the security check, arrived at the center when Foster was out-known information-doctored or replaced, and left. Under six minutes to come in, walk up, go in, do it, walk out. I’ve timed it.”
    She stopped again, turned a circle. Puffed out a breath. “It’s possible it could have been done by one of them without being seen. Low risk, as if they had been seen, their kid goes here. Any handy excuse or reason to be on site would have passed without a blink.”
    “But they weren’t seen.”
     
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    “No, they weren’t. Straffo was in his office off and on that morning, door closed. Did he slip out, get over here, and do it? Possibly-very tight, but possibly. Allika was shopping.
    Same deal. However, Allikawas seen on the day Williams was killed. Signed in, hung around.”
    Again, he followed her reasoning. “If she decided to eliminate teachers,