The Third Season finale of Only Murders in The Building was as stellar as the previous two conclusions on the show, even if it was more emotional than the other two. Branching out slightly from the mysterious and murder-prone Arconia, Season 3 was tied together with a thread of motherly love as the real perpetrators behind the double murder of Ben Glenroy were caught and exposed.
Source:https://www.cbr.com/10-only-murders-in-the-building-twists/