Question: Since Harry knew about Dexter's homicidal tendencies, why would he train Dexter on how to kill people who got away with their crimes instead of taking him to a psychologist?
Question: The DNA test is a match, but later in the 2-3rd season we discover that Harry (foster father) had an affair with the real mother. Is Harry the real father and takes him but not his brother in because of that or not?
Answer: No, Harry is not the real father. While he did have an affair with Dexter's biological mother (Laura Moser), this was when she was his C.I. Dexter was already born at that point.
Question: Dexter tests the blood on Miguel's shirt, to see if it's Freebo's. It looks like he's just using a DNA sequencer and the blood result comes back "bovine." Can a DNA sequencer differentiate which species the blood came from like that? Or perhaps he was using a different type of blood analysis machine? Is there an analysis machine that's capable of that? I thought the way to test if blood is human or not, "anti-human serum" is mixed with the blood to see if it will clot. So wouldn't the only way to tell it was bovine blood is to inject it with "anti-bovine serum"?
Answer: The short answer is yes, it could. but, it would have to be set up to analyze results to differentiate species. The sequencer will report the base pairs for any properly prepared sample, but interpreting the results is a software package. The software is available, but I would think it unlikely that an analysis package used in a forensics lab would have the capability to be so specific. More likely it would report "Non Human Sequences Found."
Dirty Harry - S4-E5
Question: In some episodes they mention an officer's romantic relationships can be used by attorneys to somehow discredit the officer and get the suspect off. In this episode specifically, Deputy Chief Matthews says the department can't risk a defense attorney turning Lt. LaGuerta and Sgt. Batista's romantic involvement a courtroom sideshow every time they work a case together (and thus Batista needs to be transferred out of Homicide). But why would it matter? Is this just "Hollywood" exaggeration for plot purposes? Wouldn't the prosecution object based on relevance if the defense attorney tried to bring this up, especially since Lt. Guerta disclosed the relationship through the proper channels? Or is Matthews lying for an ulterior motive.
Answer: It could be a combination of both. Defense attorneys will do just about anything they legally can to get their clients acquitted, so it's not unreasonable that they might try to convince a jury that a romantic relationship between two officers in the same precinct could somehow cause problems for a case. Even if it's unlikely to work, the department would want to avoid it altogether. Additionally, Matthews and LaGuerta don't particularly like each other and are shown multiple times throughout the series to be scheming against each other, so it could just as well be a power play by Matthews to put LaGuerta in her place.
Answer: Two reasons. First, as a cop he knows that there are lots of murderers walking around free due to flaws in the system so he uses Dexter's "urges" to right the wrongs in the system by taking out people who have no right to walk around free. Secondly, by taking him to a psychologist he runs the risk of having him committed and he doesn't want that for obvious reasons, so he figures it is best to channel his urges to what he considers a greater good.
The_Iceman
In addition to the earlier answer, in the last season (8th) of the show, we are introduced to Dr. Vogel, whom Harry had been discussing the situation with Dexter as well, and it is shown on-camera that Harry describes what Dexter has done (killing)... So, technically he did consult a psychologist/psychiatrist, just not having Dexter and her actually meet. But Dr. Vogel was aware of whom it was and how to intercede.