He shall take cognizance of all violations of law and of orders of courts, tribunals or commissions affecting the general welfare of the people, including combinations, agreements and unlawful practices in restraint of trade or for the suppression of competition, or the undue enhancement of the price of articles or commodities in common use, and shall institute or cause to be instituted such criminal or civil proceedings before the appropriate state and federal courts, tribunals and commissions as he may deem to be for the public interest, and shall investigate all matters in which he has reason to believe that there have been such violations.