The team eventually discovers the true killer is a man with a violent past who had been following the victim.
While several shows have an episode titled or a similarly named finale, the most prominent match for Season 4, Episode 12 is Chicago P.D. Chicago P.D. — " Sanctuary " (S4E12) [S4E12] Sanctuary
The series finale is a two-part episode titled " Sanctuary for None ." Episode 12 of Season 4 is " Sanctuary for None, Part I ," which features a massive confrontation between Magnus and Caleb as the Sanctuary faces destruction. The team eventually discovers the true killer is