Rashi on Deuteronomy 21:7/רש"י על דברים כ״א:ז׳

1ידינו לא שפכה [AND THEY SHALL ANSWER AND SAY,] OUR HANDS HAVE NOT SHED [THIS BLOOD] — But would it enter anyone’s mind that the elders of the court are suspect of blood-shedding?! But the meaning of the declaration is: We never saw him and knowingly let him depart without food or escort (if we had seen him we would not have let him depart without these) (Sifrei Devarim 210:2; Sotah 45b). The priests thereupon say (next verse): כפר לעמך ישראל FORGIVE UNTO THY PEOPLE ISRAEL.