Ceffa, a member of the League party in his second term, was one of five public officials placed under house arrest.
The officials are charged with crimes against the public administration.
The residences of two other people involved in the investigation, a former member of the European Parliament representing the League party and a construction entrepreneur, were searched by police as part of the operation on Thursday.
The probe kicked off in November 2022 when, in an attempt to overthrow the municipal government, a councillor was allegedly offered 15,000 euros to step down.
The mayor, to have the support of another councillor, allegedly offered her a job as a consultant, investigative sources said.
Deputy Prime Minister and Transport Minister Matteo Salvini, the leader of the League party, said on Thursday that he knows Ceffa “as an honest and correct person at the exclusive service of the city”.
Salvini said he and the party stood by his side, “certain of his integrity” and “sure that he can prove his total innocence”.
ANSA
