Meanwhile, Nicky's pried Gil out of the van so he can share his discovery about the expertly-faked van registration. Gil's not pleased to learn that they're no closer to knowing who owns the van, and Nicky whips out the Reagan-era parking pass. He recounts how he called the school to find out who owns the pass, and tells Gil, "Not a student, but an employee executed two years ago." Gil's all, "John Mathers?" None other. The van matches the partial VIN Nicky was able to scare up. Gil's a little gobsmacked by this: "So our killer's driving around in Mathers' old van." Nicky offers the smartest theory anyone's trotted out regarding the baffling pattern of killings: "I don't think these two guys were an original and a copycat. They were partners." Gil's expression is illuminated by the light bulb that just went off over his head.
Nicky then scampers off to re-watch interviews with Mathers, where the guy's explaining how killing him won't solve anything. Catherine comes over to watch, and I brace for the inevitable flashback, since what would a Season Five episode be without the moment where Catherine yanks the focus around to herself? Surprisingly, this scene goes on with Gil and Sara coming in to watch as Mathers continues to assert that the real killer's still out there. Sara breaks the post-interview silence by sharing the news that the prints on the comic books' comb bindings match the prints pulled from the van. Remember, those match the prints pulled from the trash bag, so the artist-killer connection's been forged with two different pieces of evidence (the ESDA and the prints). Gil asks if Sara analyzed the comics, and she replies, "Yeah, and the drawings indicate a dominant, disassociative sexual sadist." I probably shouldn't find it so amusing that she looked at Catherine while saying that. Nicky points out that the prison doc found Mathers to be a psychopath with a dependent personality disorder. Also, it's kind of funny that Gil's glaring at Nicky while the Young Turk makes that assessment. Silly Gil! We all know Nicky has rage issues, not a dependent personality disorder. Sara bolsters Nicky's theory with, "Which means [Mathers] was predisposed to violent crimes, but he might have needed some encouragement." Gil points out, "To invite someone to join you for torture and murder would require a great deal of trust." Really? You can't just post it on Craigslist? Gil continues, "You would only do it if you could completely control your partner." Catherine concludes that Mathers' partner was the alpha male. Gil elaborates: "Sexual sadism can go hand in hand with sexual dysfunction. Mathers said that he wasn't the killer. But we know he had sex with Charlene Roth based on the fact that we found his pubic hair on her body." Catherine corroborates the Mathers-as-murderous-marital-aid angle by pointing out that the beer bottles found in the van tested positive for a vaginal contribution, so the Blue Paint Killer's now achieving rape via objects, as his detachable penis got a lethal injection a few years ago. Nicky voices as much: "Maybe Mathers was this guy's surrogate penis." Sara looks squicked by that, then looks down like she's working on a crossword puzzle. Catherine continues that the one thing throwing off the theory is that there was no killing last year, and Gil points out that occasionally, life gets in the way of performing hideous ritualized murder.