Papal Legates with plenipotentiary authority were sent to Languedoc, and decrees were issued against the heretics, in which the Inquisition was rather implied than directly named; nor can I find that S.Dominic, though he continued to be the soul of the new institution until his death in 1221, obtained the title of Inquisitor.
Notwithstanding this vagueness, the Holy Office may be said to have been founded by S.Dominic; and it soon became apparent that the order he had formed, was destined to monopolize its functions.

The Emperor Frederick II.

on his coronation, in 1221, declared his willingness to support a separate Apostolical tribunal for the suppression of heresy.

He sanctioned the penalty of death by fire for obstinate heretics, and perpetual imprisonment for penitents--forms of punishment which became stereotyped in the proceedings of the Holy Office.[78] The tribunal, now recognized as a Dominican institution, derived its authority from the Pope.

The bishops were suffered to sit with the Inquisitors, but only in such subordinate capacity as left to them a bare title of authority.[79] The secular magistracy was represented by an assessor, who, being nominated by the Inquisitor, became his servile instrument.