I just noticed how some of the best TV shows/series I've watched are in some way police or detective themed. There are three main examples I'll bring and all of them are highly rated as well. Note that this is not a review, so I'm not going deep into each one.
First off, "True Detective" season 1. This show is magnificent and I still can't wrap my head around how good it was. I also watched the second season, which was good as well, but not even close to the first one. I have to say, possibly one of my favourite shows ever.
Secondly, "Dexter". When I started watching the series I became completely obsessed from the start. The way the series was just shot, the plot and the characters - amazing. I also think that the spin offs are pretty nice, although I don't really understand why "New Blood" and "Resurrection" couldn't be just one show.
Finally, "Twin Peaks". Just recently finished it and I'm very surprised I didn't discover this peak show earlier. This surreal, dream like theme that the show has is so unique and cool and I definitely have to discover more of David Linch's filmography. I have to admit though, in my hurry to season 3 I accidentally skipped "Fire Walk With Me", so I have to watch that as well.