[2] His father's brothers were Archbishop John X of Ravenna and Otto, a patron of the monastery of San Savino in Piacenza.
[6] It has been suggested that Sigulf, a "man of good character" (vir bonae indolis) who, according to the Annals of Quedlinburg, had his election as bishop of Piacenza quashed to make way for Philagathos, was the same person as Siegfried.
This seems to have been done to strengthen Siegfried, who was regarded as an ally by Otto III, who had entered Italy with an army to depose John XVI earlier that year.
[14] Siegfried also rebuilt the basilica of Sant'Antonio, which he dedicated on 20 March 1014 in a public ceremony attended prominent local figures, including Count Lanfranc.
[17] The relics of Saint Justina were transferred to Piacenza by Philagathos, but Siegfried held a formal procession to receive them in their final resting place on 17 August 1001.
[19] Around 1006, Siegfried also commissioned a written account in Latin of the transfer of the relics, the Translatio beatae Iustinae.