The commissioner shall have power:

(1) Before granting a permit to any applicant to investigate the character and standing of such applicant;

(2) Upon the receipt of any verified complaint from any person pecuniarily interested showing or tending reasonably to show any violations of any of the provisions of this chapter, to investigate fully any transaction involving solicitation, receipt, sale or attempted sale of any farm products and, in furtherance of any such investigation, to require the production of and inspect or take copies of that portion of the ledgers, books, accounts, memoranda and any other documents belonging to or under the control of any commission merchant and bearing upon such transaction and, in the course of and in furtherance of such investigation, to require of any commission merchant a sworn statement of all the material facts relating to any such transaction. It shall be the duty of every commission merchant, upon reasonable request of the commissioner, to produce for his inspection memoranda and other documents aforesaid and to make and deliver to the said commissioner upon his request a sworn statement of all the material facts; and

(3) Upon reasonable grounds for believing that any commission merchant has committed some act or is in such a condition as to justify the revocation of his permit under the provisions of this chapter, to cite such commission merchant to appear before the commissioner and show cause why his permit should not be revoked for the reasons specified in such citation. Service of the citation may be personally or by registered or certified mail at least seven days before the hearing, which shall be held in the city or town in which is situated the place of business of the permittee. The commissioner, at such hearing, shall have power to administer oaths to and take the testimony of parties and any witnesses there produced for or against the permittee. Within 10 days after the hearing, the commissioner shall render his decision dismissing the proceedings or revoking the permit. It shall be the duty of the commissioner, immediately on the entry of such decision, to send by registered or certified mail a copy thereof to the permittee at the latter's business address.