So stupid Harry is hanging with Dexter as he cleans his boat, and this is easily the worst part of another jam-packed episode, so suffice it to say that despite the fact that Harrison is apparently coming home soon and Deb has been off Dexter's back, Harry feels the need to torture a metaphor about the ocean and the waves and the salt water and SHUT UP. However, we get somewhere when Dexter discovers some blood left behind from the timely exit of one Louis Greene from this show, and aspersions toward Jason Gedrick's cleaner abilities aside, has it not rained in Miami in the weeks since Greene became the victim of his own video-game concept? Now that something is actually happening, Harry is nowhere to be found, but Dexter gets out his forensics kit and quickly realizes a murder about which, for once, he knows nothing happened on his boat. He takes a sample.
Oh, look, here's Masuka whining to Quinn, of all people, that he should tell him if he knows anything about him getting fired, like, since when do these two even talk and why would Quinn know anything about anything? If he were still dating Deb, I could see it, but I barely remember that even happened at this point. Quinn apparently can't stand Masuka to the same degree I can't, which is definitely causing me some cognitive dissonance, and after Masuka blathers about how he took a paralinguistics course and he can tell Quinn is lying, Quinn positively barks at him to go away, and at least Masuka understands people's vocal cues enough to know he's not kidding around.
However, Masuka runs straight into Deb and asks her if he's getting canned, and she does seem like the logical person to whom to direct this question, so I still don't know what all this nonsense with Quinn was in aid of, but Masuka does actually have a reason for running around like a headless chicken in a state of arrested development, as he learned from a friend about LaGuerta farming out the Colin Hanks blood slide to a private lab. When Deb hears Masuka babble those certain keywords, she obviously silently freaks, but she holds it together enough to assure Masuka that LaGuerta is probably just alleviating his workload and that she'll look into it...
...which she does, immediately. LaGuerta dissembles at first, but when Deb's sharp eyes spot Keith Carradine's FBI notebook sitting prominently atop LaGuerta's desk and Deb asks if LaGuerta might be checking into the Bay Harbor Butcher case, LaGuerta gives her an appraising look and then has her shut the door and have a seat. She asks Deb for confidence before telling her about the slide with Colin Hanks' blood on it and her theory about the BHB still being alive. Deb weakly points out that Colin Hanks' death didn't exactly fit the MO of the other BHB kills, but LaGuerta's counter is that the fact that the BHB kept blood slides was a detail that was never made public, so the chances that someone else would have copied the MO are almost nil. Of course, if the BHB were in law enforcement, there's no reason to think a copycat couldn't be as well, and a law-enforcement officer could have been privy to the info; still, LaGuerta's theory has merit even if you don't know what Deb does, which is borne out by Deb admitting that she can't come up with any other theory that fits the facts.