It is revealed that the poison was specifically keyed to Rodian physiology. Since both the victim (Farr) and his assistant, Lolo Purs , are Rodians—but only Farr died—Padmé realizes Lolo faked being poisoned.
This episode is actually the conclusion of a political arc that begins in Season 3. For the best narrative flow, IMDb reviewers and Wookieepedia suggest watching in this order: S3E10: "Heroes on Both Sides" S3E11: "Pursuit of Peace" S2E15: "Senate Murders"
Watch a detailed breakdown of the political intrigue and the mystery behind the poisoning of Senator Farr:
Despite the killer being caught, the bill to stop clone production ultimately fails, illustrating Palpatine’s growing grip on the Senate.
