Here's how every episode goes in a nutshell:
Someone is killed
Detectives immediately begin interviewing the usual suspects (boyfriend, ex-husband, ex-employee, etc.)
The detectives go down the list until alibis, DNA evidence, surveillance footage, etc. Eventually rule out each "usual suspect"
After they've wasted all that time and ruled out everyone on their suspect list they do a modicum of actual investigative work and end up finding the "unexpected killer", which actually translates to a completely unrelated and impossible-to-expect person
It really highlights the way investigators like to say everything is suspicious. Your timeline doesn't match what your friend says about the timeline? Suspicious. Your timeline DOES match what your friend says about the timeline? Suspicious. Eventually when everyone has a solid alibi--or my personal favorite, knows their rights and/or has an attorney--they move on, all the while wasting time trying to throw darts and make something stick. It's only until after all that is exhausted they do something simple like find a DNA sample, run it through a database, and find a suspect that wasn't on their radar at all. In the meantime, you get to watch investigators try to coerce false confessions out of innocent people.
Basically an unintentional expose into the stupidity and laziness of modern police investigations.
