Dexter heads out into the bullpen to hand LaGuerta the hammer model that was used for the murder. (I'm assuming he went and bought one and didn't hand over the actual murder weapon.) He says he needs to cut out early to deal with a personal matter, and these days, LaGuerta is more than sympathetic to such a concern.
Meanwhile, Quinn checks in on Deb and asks if she still means to testify against Nikki. Deb says she changed her mind and thanks Quinn for talking her out of it. Lucky for Deb, she's moved onto a new obsession: Maybe Nikki Wald really didn't kill Lundy. She went and checked Lundy's personal effects and saw how much of his Trinity-hunting materials were missing (absconded by Dexter, in fact, but she doesn't know that). Quinn, as ever, is dubious about this whole Trinity thing and tells Deb she needs to drop it before she drives herself crazy. Deb's all, "I'm gonna end up going crazy about something, why not this?" Paraphrasing, but that's the point. Quinn backs away slowly.
Angel and LaGuerta show up in Matthews's office having made a decision: They're no longer seeing each other. They've signed affidavits to that effect, insuring the department against legal action. So there should be no reason to keep either of them out of Homicide. Matthews stresses that if this is just a lie to get him off their backs, it'll have repercussions. Career-ending-type repercussions. Angel and LaGuerta appear resolute. Getting off the elevator back down in Homicide, they part with some tension, LaGuerta repeating, "It's over." Is it, Maria? Is it? (No, seriously, is it?)
Dexter's back at his Murderer Pad, staring at the last few boxes yet to be moved. These would be the most Dark Passenger-intensive items: the Trunk O' Murderin' Tools, the Box O' Blood Samples, various articles of clothing (murderous clothing, no doubt), and Lundy's research on Trinity. DVO muses that if he doesn't find a way to successfully hide this stuff, it's all over for him. Turning back to the Trinity stuff, Dexter gets an idea. He does a records search for obits where the deceased was survived by Arthur Mitchell. He comes up with three: Vera, Marsha, and Henry Mitchell. Vera: Arthur's sixteen-year-old sister who was found dead in a bathtub. Marsha: Arthur's mother, who jumped to her death off a bridge. Henry: Arthur's dad, who was beaten to death in an alley. Well, that all fits really, really neatly, doesn't it? Not sure why Dexter's so floored (he is literally lying on the floor right now), given the pedestrian nature of this discovery. DVO notes how Arthur's easy symmetry to his killings reflects Dexter's own: He saw his mother get cut up, now he cuts people up. Fair enough, DVO. Looking over his blood slides, Dex pledges to find where Arthur keeps his own incriminating artifacts.