Mauri had been in jail since he was was arrested on May 28 on suspicion of sporting fraud and fraudulent association along with former Genoa midfielder Omar Milanetto, now with Serie B side Padova, who was also granted house arrest on Monday.
Judge Guido Salvini said aspects of Mauri's defence were "scarcely plausible" but the case for keeping him in custody had still been "considerably reduced" after questioning.
Both players were arrested in connection with fixtures last season between Lecce and Lazio, and Lazio and Genoa.
Salvini said that, as a result of the interrogations, "dark clouds" now also hung over last season's derby between Genoa and Sampdoria, though this game was still not being officially investigated.
The widening scandal has also seen Antonio Conte, coach of championship-winning Juventus, placed under investigation over allegations relating to a 2011 match between his previous club Siena and Novara.
Italian coach Cesare Prandelli dropped former Genoa defender Domenico Criscito from the squad for the upcoming European Championship in Ukraine and Poland after it was announced he was also being investigated. Criscito now plays in Russia for Zenit St Petersburg.
Prime Minister Mario Monti suggested Italian professional football should be halted for two or three years to get over the scandal, but the idea was dismissed by the football federation and several big clubs.
