‘Only Murders in the Building’ Season 3 ending: Who was the killer?

nypost.com:

Spoilers ahead for the Season 3 finale of “Only Murders in the Building.” The murderer was … Clifford “Cliff” DeMeo (Wesley Taylor), the young Broadway producer of Oliver Putnam’s wacko mystery musical “Death Rattle Dazzle.” Well, OK, the crime was mostly committed by Clifford.

In Episode 10 of the third season of “Only Murders in the Building” — the Hulu series’ cleanest wrap-up so far — viewers learned that the homicide was essentially a two-man job.

The deadly act began with Cliff’s producing partner mother, Donna (Linda Emond). After reading a leaked, scathing review before the first opening night of “Death Rattle,” which began as a play revival starring Ben Glenroy (Paul Rudd), a famous comic book movie actor, ruthless Donna sprinkled rat poison on a cookie and gave it to Ben.

But not with the intention of offing him — she only wanted to save her show by sidelining the lousy lead.“I wasn’t trying to kill Ben, I was just trying to knock him on his ass,” she admits to scrappy podcasters Oliver Putnam (Martin Short), Charles Haden-Savage (Steve Martin) and Mabel Mora (Selena Gomez) after they confront her with their evidence. “To buy us some time.”Then on the very same night of the poisoning, after Ben’s miraculous recovery, the aptly named Cliff pushed Ben to his actual death down the Arconia’s elevator shaft during a heated spat.