In the lab at Miami Metro, Dexter has apparently promoted himself to Medical Examiner, as he bustles around while Deb tells him they have an ID on the victim -- Nathan Roberts, who went out for a jog and never came back. No word on if he had a wife and kids in Baltimore. Dexter eagerly reports that the kill wounds on the Jogger Who Went To Pieces and the Beasts In The Belly guy match, and then references the ME's report, which is weird, because if Dexter isn't doing ME work, shouldn't his analysis be confined to matters of blood spatter? Whatever, there's enough to cover here without worrying about Miami Metro's internal jurisdiction matters. The point is that there was some residue in the wound, and a report on same is forthcoming, as are the measurements of the wound (I guess his examination was strictly visual? Not caring.) before speculating that a bone saw was used to cut off the victim's arms and legs. I know it's early for such bad puns, but I feel I'll cause myself internal damage if I don't congratulate Dexter for going out on a limb there. He then notices something wedged down in one of the victim's lower eyelids, and when he extracts it, we see it's a piece of paper with the numbers "1242" on them. And I'd laugh about the killer(s?) making it so hard to find this clue after the grand parade he (they?) just put on, but whether or not real serial killers do this, the idea at least has its roots in Twin Peaks and Silence Of The Lambs, which obviously is all that really matters.
This gives Dexter the idea to check the first victim for a similar message, and when he comes up empty on the body, he thinks to check the guy's eviscerated intestines, and I'm sure the props master was just thrilled to have to keep those on ice for this long. I will, however, say that it's enjoyable that Deb doesn't even bother commenting on how much Dexter gets off on sick shit like this anymore. Anyway, "1237" is the number Dexter finds, and by the way, the slip of paper it's written on so strongly resembles one you'd find in a fortune cookie that I can't believe no one made a sick joke about it. Deb can't believe she's been on her new job less than a week and already has a crazy serial killer to catch, but Dexter corrects her that he needs to commit at least three separate killing events to qualify. Deb looks at him incredulously, but you can see where he'd want to preserve the integrity of the definition. He then gets a call from Jamie saying Harrison isn't feeling well -- she doesn't think it's anything bad, but she wonders if she should cancel his play date. Dexter tells her definitely and she should call him if he gets any worse, like, he's bawling his head off, so I guess screaming will be the next call? If so, can it happen off screen?