I started watching this show this summer on Netflix. It has 4 seasons on Netflix, but was originally shown on AMC.
The show is one of the best cop shows I have watched in a long time. The writing is tight, the plot placing is great, the acting is perfect, the characters make you care, and it is very believable. In some ways it reminds of the Wire, but more suspenseful and without the ghetto.
It takes 2-3 episodes to get into, but once you do, it is an amazing show. If you are looking for something great to watch, give The Killing a try.