...[O]ne of the versions of a charter of Ioannes III Duke of Naples, dated 18 Jul [949], names "domina Maria monacha filia quondam domini Marini lociservatoris, postmodum…monacho visavio vestro" (the latter relationship referring to "domino Iohanni Domini…consul et dux", who issued the charter). Stasser point out that "visavio" would normally translate as great-grandfather, and that the paternal great-grandfather of Duke Ioannes III was Duke Gregorius IV. He suggests therefore that the term may have been used in that document in the more general sense of ancestor and that it may refer to the otherwise unknown father of Duke Gregorius IV. However, the Latin of the charters of the early dukes of Naples appears to be precise and correct. In order to give "visavio" its ordinary meaning, another possibility would be that Marinus was the great-grandfather of Duke Ioannes III either through the duke´s mother or his grandmother, the wives of Dukes Marinus I and Ioannes II, neither of whom is known. This would not exclude Marinus being descended from Sergius I Duke of Naples, as cousin marriages would not be surprising in this family. Such a relationship would also preserve consistency with Marinus bearing the title lociservator, which was given to younger sons of the dukes of Naples. If this hypothesis is correct, from a chronological point of view, Marinus would most likely have been the brother of Duke Gregorius IV. 1
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