But an outstanding fine that he owed had been paid, bringing his release date forward to September 17, Wolters said, without giving further details, including who had paid it.
News outlet Der Spiegel has reported that the €1447 ($2803) fine was related to offences including document forgery and assault and that, as Brueckner had been unable to pay it, he was sentenced to extra time in jail.
But it was paid earlier this month by a woman who had worked in a police department that had been involved in fitting bugs to eavesdrop on Brueckner in his jail cell, Der Spiegel said.
The unidentified woman had told Der Spiegel she had made the transfer but that it had been a “misunderstanding” and that she had tried in vain to reverse it.
Wolters, however, said that “if someone thinks they paid by mistake, they can of course contact us and we will look into it”.
“If it turns out to be a wrong transfer, it can of course be reversed.”
Brueckner is currently serving a sentence for raping an elderly US woman in Portugal in the same seaside resort where Madeleine went missing.
He was cleared of several other charges of rape and child sex abuse after a trial last year.
Earlier this month, investigators conducted a fresh, three-day hunt in the area of the Algarve where Madeleine disappeared but did not detail the results of the search efforts.
-Agence France-Presse