Warning! Spoilers ahead for Chicago PD season 9 finale.
There's a deeper reason behind Hank Voight's (Jason Beghe) adamancy in trying to save Anna Avalos (Carmela Zumbado) in Chicago PD. NBC's police procedural wrapped up its year with the culmination of Intelligence's work against Los Temidos. Unfortunately for them, things didn't go to plan as Voight's civilian informant (CI), Anna, went rogue after getting paranoid that Javier Escano (José Zúñiga) would kill her and her son in the Chicago PD season 9 finale titled "You and Me."
Throughout the back half of Chicago PD season 9, the hunt on Los Teminos became the show's overarching narrative. Interwoven with its weekly cases, this bigger case took weeks to progress and desperately needed the help of Anna. Despite being initially reluctant to cooperate, only wanting to provide information anonymously, Voight was able to convince Anna to be his formal CI with the promise that he would keep him safe. Throughout the mission, the pair bonded and developed an almost father-daughter dynamic. All of this explains why Voight was determined to save her.
While Hank and Voight's relationship is more than enough explanation as to why he was committed to saving her, there were other reasons for the Intelligence's commitment to his latest CI. Firstly, Anna may have likely reminded Voight of Erin Lindsay. Sophia Bush's Chicago PD character had a special relationship with Voight aside from being her boss. Voight saved Erin from her drug addict mother and helped set her on a straight path. Essentially, he and his family adopted Erin and treated her as their own. Voight has always been known to have a soft spot for those who are unfairly treated or powerless, particularly ones who are committed to getting their lives together. Voight saw that commitment to have a better life than what she had in Lindsay, and he recognized that again with Anna, especially since she had a son.
Secondly, Voight had already been carrying the guilt over losing a past CI. Chicago PD season 6 introduced Lexie Wright (Cynthia Rodriguez), who was originally Alvin Olinsky (Elias Koteas) and Voight's CI. While this was the first time she appeared on the show, it was clearly established in the Dick Wolf-produced procedural that she had been working with Intelligence for a while, given her good rapport with everyone. So, when she went missing, Voight and his team did everything they could to save her. Tragically, they were too late as she was killed by a serial killer. This devastated Intelligence, but more so Voight, considering that not only did Lexie risk her life to help him professionally, but she also saved him during a previous mission. Anna was initially scared to help Intelligence to take down Los Temidos, but Voight was gradually able to convince her. Knowing what happened to Lexie, Voight was somehow indirectly making amends by not failing his CI.
Tragically, despite his best effort, Anna was killed in the Chicago PD season 9 finale by no other than Hailey Upton (Tracy Spiridakos) herself. It's curious how this will change Voight's dynamic with one of his best detectives in Intelligence. Regardless, it's safe to say that Anna's sad fate in the show will haunt him for the rest of his life.
Chicago PD will return for season 10 on NBC.