As the publishing industry finally lumbers into action, authors are attempting, like real-life Hercule Poirots, to assemble the suspects in the library and identify the guilty party.
It has to be proved that they are the guilty party.
If a crime occurs then there is, ipso facto, a guilty party.
McMahon's Executive Assistant Jonathan Coachman is the guilty party.
If a crime occurs, then according to the facts, there will be a guilty party.
Whoever is the guilty party – the person who said it or the accuser – [should] get their due punishment
They felt sure that he was the guilty party, but they had no evidence to go upon.