DENISON, Iowa (AP) — A western Iowa town has hired a Des Moines law firm for an investigation related to three top city employees who were put on administrative leave.

The Sioux City Journal reports that the Denison City Council voted 4-1 on Friday to approve the contract. Mayor Jared Beymer has declined to disclose the reasons for placing City Manager Terry Crawford, City Clerk Lisa Koch and Fire Chief Cory Snowgren on leave Tuesday.

He also declined to say what the law firm will be investigating. In a statement, the city described it as a “personnel investigation.” The hiring came over the vociferous objections of Councilman John Granzen Sr., who said he was outraged at being kept in the dark about the investigation.