The protest hearing as provided in section 54-72 shall be open to the public, and all testimony shall be under oath administered by a certified court reporter. The city clerk, with whom such petition is filed, shall have the power to issue subpoenas to compel the attendance of witnesses and the production of documents and to receive all testimony and documentary evidence before rendering a decision as to the sufficiency of the petition. Upon failure of any witness to obey the subpoena, the city clerk may petition the municipal court for an order compelling the witness to appear and testify or produce documentary evidence. The burden of proof at the protest hearing shall be on the protestant(s) in presenting its protest to the petition. The result of such hearing shall be mailed to the petition representative(s) and the elected officer sought to be recalled. The protest hearing shall be concluded and a decision, by the city clerk or the designated hearing officer, shall be rendered not later than ten days after the conclusion of the hearing. The city clerk may call upon the city attorney's office to provide legal advice during the hearing.