After a season filled with mobsters, billionaires, secret casinos, and a severed finger, the mystery of who killed Aronia's beloved doorman, Lester Chalooka, has been solved. The season 5 finale of Only Murders in the Building not only unmasked the killer but also saved the Aronia from demolition and set up a new international mystery for season 6.
The killer was revealed to be New York City's mayor, Bo Tilman, played by Keegan Michael Key. However, in a classic twist, there were two deaths, involving complicit players. An affair between Mayor Tilman and Sophia Catchamelio, wife of mobster Nikki Catchamelio, led to a tragic chain of events. Nikki, upon discovering the affair, confronted the mayor in a secret casino, leading to a fight in which he was accidentally killed by Lester Kuca in defense of the mayor.
Lester, trying to capture evidence of corruption, took Tilman's severed finger but ended up killed by the mayor during a confrontation. Billionaires Camila White, Bash Steed, and Jay Flug aided Tilman in disposing of Nikki's body to protect their plan of demolishing the building for a casino.
The trio - Mabel, Charles, and Oliver - solved the mystery through a crucial clue from Lester’s wife, Lorraine, and a garbled text revealing Lester's final message was "It's Bo Tilman." This exposed Tilman and the billionaires, leading to their arrest.
The final scene of the season shifts focus to a new case with Cinda Canning's podcast, hinting at a murder mystery in London and concluding with Cinda found dead outside the Aronia. Season 6 promises to explore this international murder case.