The Rosie Larsen murder case is still unsolved, the last season ended while Belko (Stan’s friend) aimed a gun at council man Darren Richmond. Season 2 stats with the same scene. Richmond is driven to a hospital by an ambulance. At the same time, detective Linden understands that Darren may be innocent, she understands it by the phone call that she got saying that the cameras on the bridge were out of service and that they cannot give her a photo shoot. But detective Holder gave a photo shoot of Darren Richmond on that bridge. So the photo must be faked.
On the second episode of the season- My Lucky Day someone drops Rosie’s backpack outside the family’s front door. The killer is still out there. Detective Holder comes to their home and takes the bag for “investigation”. When he sends the bag for the cups to investigate he replaces bags and sends his bag to investigate… Meanwhile, Sarah is back at Seattle and she asks her new lieutenant to make her the only detective for the Larsen case. In other words, she wants to leave Holder. The new lieutenant forces her to keep working with detective Holder.