Crucifixtion of Saint Peter, Caravaggio, 1600-1601, Santa Maria del Popolo, Rome

At the end of his pontificate Innocent III promulgated a decree at the Fourth Lateran Council (1215) that laid down extensive rules about how and when an ecclesiastical judge could prosecute criminals under his jurisdiction. This conciliar canon, Qualiter et quando (c.8), established basic rules for ecclesiastical judges to investigate and punish criminal clerics. Its provisions were based on a number of earlier decretal letters that Innocentís curia had sent in answer to questions that judges had posed about the rules governing court procedure. In Qualiter et quando two biblical passages justified Inquisitio:  Genesis 18:21 and Luke 16:2

Genesis 18:21 "Descendam et videbo utrum clamorem qui venit ad me, opere compleverint, an non est ita, ut sciam."

Luke 16:2  "Et vocavit illum, et ait illi: quid hoc audio de te? redde rationem villicationis tuae."