Cut to Gil examining the painted rail in the dark and asking peevishly, "Why didn't Nicky find this before?" Catherine tells him Nicky was working from a campus security schematic that didn't have the rail listed, which is our first clue that all is not what it seems with said rail. She then inspects the base of the railing and notes that the cement fixing it in place is still fresh. Gil says in a tone of great upset: "So now he's not just painting railings, he's installing them!" You know, considering that this guy later goes on to rape and murder women, doing a little freelance landscaping seems like the least of the guy's crimes. Gil decides they need to dig up the railing, cement and all. Perhaps then they can search the fixture for clues as to how someone smuggles a whole railing onto campus and installs it without anyone apparently noticing.
The two then head over to the water fountain they know will be nearby, and propped up next to it is a black trash bag. Something that appears to be blonde hair is sticking out. The music gets all dramatic for a moment as Catherine opens the bag, and then a sex doll pops out. Duh-DUNH-duh! Gil looks supremely peeved, and his voice reflects that as he snots, "He knew we would find this, and now he's taunting us." Catherine's got a look like, "Gil, that's just the reaction he wants. Don't give him the satisfaction."
And then those two head back to the lab for the second montage of the night. It's basically an excuse to show a sex doll on prime time network TV before the indecency fines triple for all offenses, real or imagined. And to bring in the cast of Stomp to run fingerprints through CODIS, if the soundtrack is anything to go by. Nicky works the railing during the montage; Catherine and Gil process the sex doll as if she were a real woman. (Insert your own Real Doll joke here.) Catherine eventually finds the folded-up note in the doll's mouth: it reads, "I HAVE HER."
Gil and Catherine look at each other, appalled by the realization that the Blue Paint Killer's got another victim. As Gil lifts a single human hair off the note, Catherine notes somberly, "Two years ago, DNA found a hair on Debby Reston that belonged to the serial's first victim, Janet Kent." Gil prods our memories of sweeps periods past with, "Planted hairs. It's his signature."