I think the evidence is pointing toward the former happened, on the part of roughly 592 ballots all being voted by the same person.
I think there is evidence the latter may have happened, as election officials approved these ballots with little oversight and a significant number of ballots in the congressional district were requested but then never returned. I believe there is more information to be gathered to determine if Dowless was the same person that voted absentee repeatedly and the person that (possibly) collected and destroyed minority ballots.