"So the chief priests, scribes and elders answered." The word "so" marks an event that happened because of something else that happened first. In this case, they had reasoned with themselves in [Luke 20:5-6](./05.md), and they did not have an answer they wanted to say.
This could be stated as a direct quote. Alternate translation: "they said, 'We do not know where it came from.'" (See: [[rc://en/ta/man/translate/figs-quotations]])