Turkish prosecutors on Tuesday ordered the detention of 22 suspects as part of an investigation into alleged irregularities in vehicle rental tenders by the Bolu Municipality, authorities said.

The Bolu Chief Public Prosecutor’s Office said judicial proceedings were launched against 23 suspects, including suspended Bolu Mayor Tanju Özcan, over a municipal tender for the rental of driverless vehicles and construction machinery used in waste collection, transportation and general cleaning services.

Özcan, who is already jailed in connection with a separate case, was not included in the detention orders issued for the other 22 suspects.

Prosecutors said an expert report dated Aug. 25 identified alleged irregularities during the implementation of the contract. Investigators compared vehicle tracking data from Arvento Mobile Systems company with municipal landfill records and monthly work schedules.

The review found that some garbage collection vehicles were recorded as operating on days when they had not actually worked and that payments were made to the contractor based on those records, according to prosecutors.

The expert report estimated that the municipality made TL 34.29 million (about $700,000) in excess and improper payments, including price adjustments and value-added tax, to the MCY-Yeşilçam joint venture in 19 progress payments.

The investigation also covers municipal officials and employees involved in the tender, inspection, acceptance and payment processes, as well as executives of the contractor.

Police and gendarmerie launched simultaneous operations centered in Bolu across seven provinces. Gendarmerie teams also searched the Bolu Municipality building and examined tender documents, payment records and vehicle tracking data.

Prosecutors said the investigation remains underway.