The precise origin of Siegfried Count of Luxembourg is unknown but it is probable that he was related to Wigerich [III]. Gerbert of Aurillac refers to "Godefridum, patruumque eius Sigifridum" in a letter dated 985 addressed to "dominæ Teuphanu Imperatrice" after he visited the pair in prison following their unsuccessful defence of Verdun against Lothaire King of the Franks, other letters clarifying that "Godefridum" was Godefroi Comte de Verdun, grandson of Wigerich [III]. Siegfried´s birth, estimated to [930/40], indicates that he could not have been the son either of Wigerich (died [916/19]) or of Cunigonde's second husband Richwin (died [923/24]). Another indication that Siegfried was probably not the son of Wigerich is his absence from a charter dated 943, issued by the widow of Wigerich's son Gozelon, which is subscribed by the latter's three known lay brothers... [The] most likely possibility appears to be that Siegfried was the son of Cunigonde by an otherwise unrecorded third marriage. Otto I King of Germany transferred the convent of Echternach to Siegfried "advocatus altaris" in [949/50], although the charter relating to this grant has not yet been identified. Siegfried owned scattered properties in Feulen, Hosingen and Monnerich (in the pagus Wabrensis) and at Berncastel and Roussy (in the pagus Mosellanus).
Comte [de Luxembourg]. "Sigefridus comes de nobili genere natus" received the castle of Luxembourg from St Maximin, Trier in exchange for property "villa Feulen in comitatu Giselberti comitis in pago Arduenne in villa…Viulna [et]…in pago Mathingouui in comitatu Godefridi comitis super ripem Alsuntie fluminis" by charter dated 17 Apr 963. Gade reproduces a photographic copy of the original charter.
Vogt of Echternach from 973: "Otto…imperator augustus" granted property to Kloster Echternach by charter dated 15 Mar 973 which names "comitis Sigifridi fidelis nostri".
Vogt of St Maximin at Trier: Archbishop Egbert donated property "de beneficio Luthardi comitis…mortuo sine herede" to Trier St Paul by charter dated 981, subscribed by "…Sigefridi comitis et rerum S Maximini advocatis…". He captured Wicfred Bishop of Verdun, who had attacked Siegfried's territory, at Vandresel but released him in . Richer records that "Belgicæ dux Theodericus, necnon et vir nobilis ac strenuus Godefridus, Sigefridus quoque vir illustris, Bardo etiam et Gozilo fratres clarissimi et nominatissimi" captured Verdun in 985. Siegfried helped defend Verdun against Lothaire King of the West Franks in [984/85], but was captured together with Godefroi Comte de Verdun [Wigeriche].
According to the Preface of Vitæ Heinrici et Cunegundis Imperatores, "Sigefridus Kunuz comes, pater Chunigundis imperatricis, obiit V Kal Novembrisi". The necrology of Ranshofen records the death "V Kal Nov" of "Sigefridus Kunuz pater Chunigundis imperatricis". The necrology of Gorze records the death "VI Kal Nov" of "Seifredus comes". The year of Siegfried´s death is uncertain but is assumed to have been around . Siegfried is named "Siefredi Saxonum ducis" by Rodulfus Glaber when recording the marriage of his daughter to Heinrich II King of Germany. No other primary source has been identified which either accords the ducal title to Siegfried or directly links him to Saxony. The editor of the MGH SS edition of the text suggests that “all Germans called themselves Saxones” and that “all those in powerful positions adopted the title dux” ("omnes Germanos dicere videtur Saxones, omnes potentiores ducis nomine ormat"). 1