"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 ([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]])