The fifth season of Only Murders in the Building solved the mystery of Lester's murder - and revealed whose death is the focus of season 6. In the Tuesday, October 28, season finale, Mayor Beau Tillman (Keegan-Michael Key) was unmasked as the man who was sleeping with Sofia (Téa Leoni), which Nicky (Bobby Cannavale) found out. The night of Lester's (Teddy Coluca) death, Nicky cut off Beau's finger. After Nicky attacked Beau, Lester got involved, which led to Nicky's death. Lester was then hunted down by Beau because he wanted his finger back.