For the purpose of more completely discharging the duties resting upon him and to discover the truth and to make his reports truthful in all matters handled by him, the state auditor is empowered to conduct hearings, to summon witnesses, to administer oaths, to take the testimony of such witnesses, and to compel the production of documentary evidence at such time and place as he may designate for the purpose of investigating and determining the conduct and record of the employees and officials of any department of the state government.