His reign is obscure and the next judge mentioned is his son Constantine I in 1112, but to ascribe to Marianus a 39-year reign seems unnecessary and the presence of unknown other judges between Marianus and Constantine is likely.

In 1147, Marianus' grandson, Gonario II, made a donation of silver to the Abbey of Montecassino, citing his father and his grandfather as prior donors.

Similarly, the Cronaca sarda makes Marianus the son of Andrew Tanca.

The exact identity and relationships of this judge remain a matter of dispute.

Not only did Marianus make a donation to Montecassino, but he benefited the local churches as well and paid an annual sum to the papacy.