What happened to Minneapolis’ missing ballots? That’s the question of the day in the U.S. Senate recount.

Yesterday it was disclosed that 133 fewer ballots were tabulated in precinct 1 of Ward 3 during the recount than on election day. There were 2,028 votes recorded during the initial count, but only 1,896 ballots were included in the recount. The change resulted in a loss of 36 votes for Al Franken in the heavily Democratic precinct.

Elections director Cindy Reichert initially had a seemingly logical explanation for the discrepancy: ballots that included a write-in candidate were mistakenly fed through the machines twice during the initial count.

But there’s a rather serious flaw in this explanation: the numbers don’t add up. The voter roster for precinct 1 of Ward 3 includes 1,047 registered voters, 932 additional voters who registered in person on Election Day, 35 absentee ballots that were received by the city and 15 absentee ballots that were received by the county. That’s a total of 2,029 voters — or just one off the number of ballots recorded on election day. By contrast the recount tally is 133 ballots shy of the number of voters indicated on the roster. (Nate Silver has an excellent analysis of the situation at FiveThirtyEight.)

Reichert has since backed off from the double-counting of write-in ballots explanation. “We don’t know what happened,” she told the Star Tribune. “It looks like that wasn’t valid speculation.”

So the question remains: what happened to the ballots?