Administrative agencies possess various types of investigative authority. This chapter will examine the nature of and limitations on the prehearing investigative authority of administrative agencies. 
 For additional materials regarding agency investigations and subpoena power, see 1 Kenneth C. Davis and Richard. Pierce, Jr., Administrative Law Treatise § 4 (5th ed. 2010), and 1 Charles H. Koch, Jr., Administrative law and Practice §§ 3.1-3.20 (3d ed. 2010). For purposes of this chapter, the prehearing investigative authority being examined is the authority to investigate that exists before the initiation of an administrative contested case proceeding under Minn. Stat. § 14.57 (2014). Thus, there is no discussion of the right of a party to invoke the subpoena authority of the Office of Administrative Hearings under Minn. Stat. § 14.51 (2014). Discussion of that authority is contained in § 7.4.2 infra, which relates to prehearing procedures.