Chicago PD season 5, episode 22 picked up where the previous hour left off, and the guards called for an ambulance, which took him to the nearest hospital. Meanwhile, Voight was about to come clean to Denny Woods and James Osha about Kevin's murder. But before he was able to, Voight received word about Olinsky's attack. He rushed to the hospital and caught the doctors as they rushed Olinsky into surgery. Voight tried to comfort him, but all Olinsky said to him was his words from the previous episode — "I got this." However, the sergeant soon learned that Olinsky died, and he heartbreakingly relayed the news to the rest of the Intelligence Unit.
The rest of the finale focused on Voight seeking revenge for his best friend's death. He and the other detectives traveled to the jail to figure out who was behind Olinsky's murder. Surveillance footage from the attack revealed that Dietz helped orchestrate the stabbing. Dietz had been paid $5,000 to look the other way while an inmate killed Olinsky. After questioning the guard, the Intelligence Unit learned that Andre Velasco was the murderer, but the truth was a bit more complicated than that.
It took some time, but they eventually traced the money trail back to Carlos DeLeon, someone involved with the Cali Cartel. Carlos hired Andre to kill Olinsky after Olinsky worked with a DEA task force to investigate the cartel member. The investigation led to the arrest of Carlos' little brother, who died in jail. So when Olinsky got booked, Carlos sought vengeance for his brother. The Intelligence Unit tracked down Carlos, and Voight cornered him on a rooftop. Voight shot and killed him and later claimed that Carlos was reaching for a weapon, despite two eyewitness testimonies. Ultimately, Voight got away with it, but it didn't bring Olinsky back.
Even though Voight avenged Olinsky's death in Chicago PD season 5, episode 22, the world still believed that Olinsky killed Kevin Bingham. The Intelligence Unit wanted to clear Olinsky's name, so before his funeral, Voight made a deal with Deputy Superintendent Katherine Brennan. If he helped her from time to time, Brennan would write a letter of exoneration for Olinsky, which, in turn, would allow Olinsky's wife, Meredith, to collect her dead husband's pension.
Voight and Brennan shook hands on the deal, and that was that. Brennan signed the letter in season 6, episode 3, and Olinsky's reputation was restored. Regardless, Olinsky's death in Chicago PD was a tough pill to swallow, and it's one of the most heartbreaking exits in the NBC series.