It's not particularly relevant to this show or case, and probably belongs elsewhere but it ties in at least.
Homicide detectives are measured on their close rate, just like anyone in sales. So, I'm going to use that as an analogy. (Please note this is gross oversimplification) You have, broadly speaking, generally 3 types of sales folks. You have longer term relationship builders that get a few big accounts and successfully milk them (relational), you have the grinder/closers that are always building their pipeline through networking, cold calls, referrals (grinders), pressure sales and some luck, then you have the guys that manipulate the system through a lot of different ways and coast until they are uncovered (weasels). (There is the rare relational grinder but they are absolutely the exception)
You find the same in detectives. The relational tend to use existing contacts, spend time and move a little slower. Grinders tend to find a ton of possible suspects, pound pavement and investigate tons of leads. Then you have weasels that are, essentially just trying to pin it on the easiest culprit and will use immoral and often illegal tactics to "close the deal". They tend to be boastful and full of shit.
Here's the thing, its not limited to Homicide detectives nor city/state but expands to federal.
If you're ever called for questioning, get a lawyer, 100% of the time.