When watching these shows I wonder when the obvious is missed is it because of (blacked out spoiler)

poor productions or poor investigations.

For example, by the end of the first episode, it is known what means the authorities used to try and solve this case (most viewers will probably figure out the twist pretty soon).

But what I wonder about is through the program, the main undercover police officer is sold as the cream of the crop but when he is obtaining the confession of the suspect through the means of the ploy used by investigators he never asks questions of the suspect that could have proven if he had done the killing or not. For example, the undercover man apparently never asks the suspect what he did with the firearm after the killing. My point is, did the filmmakers edit this portion out if he did ask or did the undercover guy not even think to ask questions that could have proven the suspects guilt.