The sad, depressing realization is that there was no grand conspiracy behind the murder of Rosie Larsen. There wasn’t a sex scandal. There wasn’t a real political motivation. The truth is, Rosie was at the wrong place at the wrong time. She overheard a conversation about a backroom deal that Jamie (Darren Richmond’s campaign manager) was making behind Richmond’s back to further his campaign, and Jamie — who found her hiding in a room under construction — accidentally knocked her unconscious trying to shut her up. He thought she was dead, so he took her out to the island, where she escaped his trunk. He chased her down and beat her AGAIN, and AGAIN, he thought she was dead. (She was not).
This much Holder and Linden figured out. How much foreshadowing was there that Jamie was behind the death of Rosie? Very little. In fact, Jamie’s involvement didn’t really come into focus until the final minutes of the penultimate episode. He was never really a suspect. However, Holden and Linden decided to check out his alibi again, found out he was at the casino the night that Rosie was murdered, made some deductions based on a missing key card, and fingered Jamie for the murder. By the time they tracked him down, however, Richmond had won the election, and Jamie was giving him a crazed, comical, overly-acted left-field confession to Richmond that he’d killed Rosie by accident. Richmond was shocked. At that point, Holder and Linden arrive with Gwen, and Jamie says he needs to do what is best for Richmond’s political future. So, he pointed his gun toward Gwen, goading Holder to return fire and kill Jamie.
Murder solved, murderer dead, right? No. Not quite.