The character Nikki (played by Dania Ramirez) was killed off in "Alert: Missing Persons Unit" because the show's creators wanted to keep the series fresh and surprising. The showrunner Carla Kettner explained that they felt the love triangle dynamic involving Nikki had been fully explored over the first two seasons, and losing Nikki would create the biggest challenge for the team moving forward. Nikki's death was tied to a storyline involving Irish mob boss Charlie McGannon, who had her kidnapped and killed because she was going to provide evidence to the FBI about his criminal activities. This decision to kill Nikki was meant to honor her heroism and shake up the story emotionally and dramatically for the remaining characters and viewers. Nikki's death has lasting emotional and professional consequences throughout Season 3, and the show continues exploring this fallout.