In another room, the manager guy is folding faster than a metal chair at a revival rally. Long story short -- since this plotline is really more about the squick factor than any criminal scene -- the manager stuffed Cartsen in a large duffel bag, zipped him up, and rolled the bag down a very steep hill. "I figured he'd get out once he slept it off," he rationalizes. Nicky, predictably, looks saddened and shocked at this line of reasoning. "Treating another human being like garbage isn't a job. It's a choice," he says. The manager looks as stunned as if someone had just bothered to explain the Grand Unification Theory using only small words. Thus endeth the B-plot.
In the A-plot, Dennis wanders into CSI Central and flags down Gil and Catherine. "I need to talk to you," he says, his eyes the size of saucers. Whoever is playing this kid is doing an excellent job; get him on a Judd Apatow coming-of-age show, stat! Dennis explains that he had gone back to the school to pick up a book; he registered the spray-paint on his locker, then took a pit stop. He heard the glass breaking and watched the crime; he fled immediately. "Now my dad's freaking out, my sister won't come out of her room, I figure...if you can get the police to make some kind of deal for her?" Catherine swallows hard before pointing out, "Well, Dennis, you haven't explicitly said that you saw Kelsey shoot the victim." "She was in a stall! I couldn't see her," he points out. Just then, Brass comes in and drags the CSIs out; it turns out that Kelsey was "otherwise disposed." This phrase is delivered with typical Brass drollery. It turns out that Kelsey's idea of "looking out for her brother" was synonymous with "sleeping with Schickel's football coach as leverage for asking him to intervene." My God! This is like a bad Lifetime movie! They could call it Lateral Negotiation or something. Brass finishes by pointing out that Kelsey may be many things -- a strategic thinker being noticeably absent from that list -- but she's no killer. Gil goes back in to tell Dennis his sister is no killer; Dennis is relieved. "But then who was it?"
The question is answered in the last scene -- it's the guidance counselor. Gosh, if she weren't looking out for all those kids, she could have pinned this on the Fram siblings based on circumstantial evidence. Instead, what we get is an ending worthy of Agatha Christie -- information withheld from us, the audience, until the crime-solver decides we need to know it. It turns out that the guidance counselor feared that Barry Schickel might have incited someone to kill, kill, kill, just to get relief from bullies. She figured that killing Schickel herself was a way to prevent someone else from going berserk. "I just thought that one life was better than twenty, or thirty," she justifies. "Or eleven," say Gil, playing his I-have-information-the-viewers-don't card. "Tetrick High School, Tetrick, Arizona. Eleven kids shot a few days after Columbine. You were the assistant principal," he continues. "I watched them die at my feet, just because some sophomore couldn't take the jokes about his glasses," she says. Gil looks at her with no small amount of compassion and says, "It says that you were left with post-traumatic stress disorder. You might want to mention that to your lawyer." She shakes her head no, saying, "I did this for my kids." Gil reminds her that eventually, high school ends for everyone, and leaves. The cops descend to arrest her during school hours. Meanwhile, Sara showers with lemons (Liam is undoubtedly whimpering outside the door) and Nicky is signing out Cartsen's belongings, saying, "Rest in peace, Lieutenant." And in one last, unexpectedly sweet touch, we see Gil filling out a grant form for funding to buy the Cyranose 320; he fumbles for stamps in his disorganized desk, and Catherine stops in only long enough to extract a roll for him and then leave silently. As Gil seals the envelope, Warrick stops in the doorway, goes to say something, then thinks better of it, drifting off and leaving Gil alone.