SACCONI, RANIERO. — Dominican inquisitor, b. in Piacenza at the beginning of the 13th century, d. 21 July 1262.
Educated in heresy and leader of heretics, through the efforts of PETER OF VERONA he abjured his error and donned the Dominican habit (1245). From that time he collaborated with St Peter in the repression of the Cathars. By chance he escaped the plot contrived against him and Peter of Verona, in which the latter fell as a martyr (6 Apr. 1252). From 1254 he was head of the Inquisition in Lombardy. In 1259 he was forced to leave Milan because of the opposition of the new podestà Uberto Pallavicini. On 21 July 1262 Urban IV summoned him to Viterbo so that he might give an account of his inquisitorial activity in Lombardy.
He wrote (in 1250) a *Summa de Catharis et Leonis seu de pauperibus de Lugduno* (ed. in E. Martène-A. Durand, *Thesaurus novus anecdotorum*, V, Paris 1717, cols. 1761-76; in Duplessis d’Argentré, *Collectio Judiciorum de novis erroribus*, I, ibid. 1724, pp. 48-57; and in A. Dondaine, *Un Traité*, cited in bibliography, pp. 64-78). It is a severe indictment of his former coreligionists; it is not properly a refutation of errors but a list of errors useful to inquisitors. The work (divided into two parts: the first devoted to the Cathars, the second, shorter, to the Poor of Lyon) is of great historical interest because, beyond the common doctrine, it enumerates the beliefs proper to the various heretical churches. It is the best source for knowledge of the doctrine of JOHN OF LUGIO.